| 2012-04-06 | vs SLN | 1 | W 5-11 | 1-0 | 1 | 46,086 | Yovani Gallardo | Jaime Garcia | Jaime Garcia | Yovani Gallardo | | 5 | 11 | -6 |
| 2012-04-07 | vs SLN | 2 | W 6-0 | 2-0 | 1 | 42,084 | Zack Greinke | Adam Wainwright | Zack Greinke | Adam Wainwright | | 11 | 11 | 0 |
| 2012-04-08 | vs SLN | 3 | L 3-9 | 2-1 | 3 | 33,211 | Randy Wolf | Lance Lynn | Lance Lynn | Randy Wolf | | 14 | 20 | -6 |
| 2012-04-09 | @ CHN | 4 | W 7-5 | 3-1 | 2 | 38,136 | Shaun Marcum | Chris Volstad | Shaun Marcum | Shawn Camp | John Axford | 21 | 25 | -4 |
| 2012-04-10 | @ CHN | 5 | W 7-4 | 4-1 | 1 | 37,265 | Chris Narveson | Paul Maholm | Chris Narveson | Paul Maholm | Francisco Rodriguez | 28 | 29 | -1 |
| 2012-04-11 | @ CHN | 6 | W 2-1 | 5-1 | 1 | 34,044 | Yovani Gallardo | Ryan Dempster | Yovani Gallardo | Ryan Dempster | John Axford | 30 | 30 | 0 |
| 2012-04-12 | @ CHN | 7 | L 0-8 | 5-2 | 1 | 36,311 | Zack Greinke | Matt Garza | Matt Garza | Zack Greinke | | 30 | 38 | -8 |
| 2012-04-13 | @ ATL | 8 | W 8-10 | 6-2 | 1 | 50,635 | Randy Wolf | Jair Jurrjens | Jonny Venters | Francisco Rodriguez | Craig Kimbrel | 38 | 48 | -10 |
| 2012-04-14 | @ ATL | 9 | L 1-2 | 6-3 | 1 | 37,408 | Shaun Marcum | Mike Minor | Mike Minor | Shaun Marcum | Craig Kimbrel | 39 | 50 | -11 |
| 2012-04-15 | @ ATL | 10 | L 4-7 | 6-4 | 1 | 30,831 | Chris Narveson | Brandon Beachy | Brandon Beachy | Chris Narveson | | 43 | 57 | -14 |
| 2012-04-17 | vs LAN | 11 | W 5-4 | 7-4 | 1 | 27,159 | Yovani Gallardo | Chad Billingsley | Jose Veras | Javy Guerra | | 48 | 61 | -13 |
| 2012-04-18 | vs LAN | 12 | W 3-2 | 8-4 | 1 | 30,189 | Zack Greinke | Chris Capuano | Kameron Loe | Matt Guerrier | | 51 | 63 | -12 |
| 2012-04-19 | vs LAN | 13 | L 3-4 | 8-5 | 1 | 30,091 | Randy Wolf | Aaron Harang | Aaron Harang | Randy Wolf | Javy Guerra | 54 | 67 | -13 |
| 2012-04-20 | vs COL | 14 | L 3-4 | 8-6 | 1 | 39,188 | Shaun Marcum | Jhoulis Chacin | Matt Belisle | John Axford | Rafael Betancourt | 57 | 71 | -14 |
| 2012-04-21 | vs COL | 15 | W 9-4 | 9-6 | 1 | 43,565 | Marco Estrada | Drew Pomeranz | Jose Veras | Esmil Rogers | | 66 | 75 | -9 |
| 2012-04-22 | vs COL | 16 | L 1-4 | 9-7 | 1 | 42,611 | Yovani Gallardo | Jeremy Guthrie | Jeremy Guthrie | Francisco Rodriguez | Rafael Betancourt | 67 | 79 | -12 |
| 2012-04-23 | vs HOU | 17 | W 6-5 | 10-7 | 1 | 36,291 | Zack Greinke | Lucas Harrell | Zack Greinke | Lucas Harrell | John Axford | 73 | 84 | -11 |
| 2012-04-24 | vs HOU | 18 | W 9-6 | 11-7 | 1 | 38,686 | Randy Wolf | Bud Norris | Randy Wolf | Bud Norris | John Axford | 82 | 90 | -8 |
| 2012-04-25 | vs HOU | 19 | L 5-7 | 11-8 | 1 | 26,778 | Shaun Marcum | J.A. Happ | Wilton Lopez | Jose Veras | Brett Myers | 87 | 97 | -10 |
| 2012-04-27 | @ SLN | 20 | L 1-13 | 11-9 | 1 | 43,063 | Yovani Gallardo | Jake Westbrook | Jake Westbrook | Yovani Gallardo | | 88 | 110 | -22 |
| 2012-04-28 | @ SLN | 21 | L 3-7 | 11-10 | 2 | 42,586 | Marco Estrada | Kyle Lohse | Kyle Lohse | Marco Estrada | | 91 | 117 | -26 |
| 2012-04-29 | @ SLN | 22 | W 3-2 | 12-10 | 1 | 45,824 | Zack Greinke | Jaime Garcia | Zack Greinke | Jaime Garcia | John Axford | 94 | 119 | -25 |
| 2012-04-30 | @ SDN | 23 | W 8-3 | 13-10 | 1 | 16,218 | Randy Wolf | Joe Wieland | Randy Wolf | Joe Wieland | | 102 | 122 | -20 |
| 2012-05-01 | @ SDN | 24 | L 0-2 | 13-11 | 1 | 19,260 | Shaun Marcum | Edinson Volquez | Andrew Cashner | Francisco Rodriguez | Huston Street | 102 | 124 | -22 |
| 2012-05-02 | @ SDN | 25 | L 0-5 | 13-12 | 1 | 15,786 | Yovani Gallardo | Jeff Suppan | Jeff Suppan | Yovani Gallardo | | 102 | 129 | -27 |
| 2012-05-04 | @ SFN | 26 | W 6-4 | 14-12 | 1 | 41,082 | Zack Greinke | Tim Lincecum | Kameron Loe | Clay Hensley | John Axford | 108 | 133 | -25 |
| 2012-05-05 | @ SFN | 27 | L 2-5 | 14-13 | 1 | 41,135 | Randy Wolf | Madison Bumgarner | Madison Bumgarner | Randy Wolf | Santiago Casilla | 110 | 138 | -28 |
| 2012-05-06 | @ SFN | 28 | L 3-4 | 14-14 | 2 | 41,796 | Shaun Marcum | Matt Cain | Javier Lopez | Tim Dillard | | 113 | 142 | -29 |
| 2012-05-07 | vs CIN | 29 | L 1-6 | 14-15 | 3 | 27,157 | Marco Estrada | Bronson Arroyo | Bronson Arroyo | Marco Estrada | | 114 | 148 | -34 |
| 2012-05-08 | vs CIN | 30 | W 8-3 | 15-15 | 3 | 28,108 | Yovani Gallardo | Homer Bailey | Yovani Gallardo | Homer Bailey | | 122 | 151 | -29 |
| 2012-05-09 | vs CIN | 31 | L 1-2 | 15-16 | 4 | 27,090 | Zack Greinke | Johnny Cueto | Aroldis Chapman | John Axford | Logan Ondrusek | 123 | 153 | -30 |
| 2012-05-11 | vs CHN | 32 | W 8-7 | 16-16 | 2 | 40,097 | Randy Wolf | Matt Garza | Vinnie Chulk | Lendy Castillo | | 131 | 160 | -29 |
| 2012-05-12 | vs CHN | 33 | W 8-2 | 17-16 | 1 | 42,339 | Shaun Marcum | Chris Volstad | Shaun Marcum | Chris Volstad | | 139 | 162 | -23 |
| 2012-05-13 | vs CHN | 34 | L 2-8 | 17-17 | 3 | 42,167 | Marco Estrada | Jeff Samardzija | Shawn Camp | Kameron Loe | | 141 | 170 | -29 |
| 2012-05-14 | @ NYN | 35 | L 1-3 | 17-18 | 3 | 20,061 | Yovani Gallardo | Miguel Batista | Miguel Batista | Yovani Gallardo | Frank Francisco | 142 | 173 | -31 |
| 2012-05-15 | @ NYN | 36 | W 8-0 | 18-18 | 3 | 22,268 | Zack Greinke | Dillon Gee | Zack Greinke | Dillon Gee | | 150 | 173 | -23 |
| 2012-05-16 | @ HOU | 37 | L 3-8 | 18-19 | 3 | 15,453 | Randy Wolf | Bud Norris | Bud Norris | Randy Wolf | | 153 | 181 | -28 |
| 2012-05-17 | @ HOU | 38 | L 0-4 | 18-20 | 3 | 15,173 | Shaun Marcum | J.A. Happ | J.A. Happ | Shaun Marcum | | 153 | 185 | -32 |
| 2012-05-18 | vs MIN | 39 | W 3-11 | 19-20 | 3 | 32,421 | Marco Estrada | Scott Diamond | Scott Diamond | Marco Estrada | | 156 | 196 | -40 |
| 2012-05-19 | vs MIN | 40 | L 4-5 | 19-21 | 3 | 42,398 | Yovani Gallardo | Carl Pavano | Jeff Gray | Manny Parra | Matt Capps | 160 | 201 | -41 |
| 2012-05-20 | vs MIN | 41 | L 16-4 | 19-22 | 3 | 33,064 | Zack Greinke | Jason Marquis | Zack Greinke | Jason Marquis | | 176 | 205 | -29 |
| 2012-05-21 | vs SFN | 42 | L 3-4 | 19-23 | 3 | 31,644 | Randy Wolf | Madison Bumgarner | Santiago Casilla | Juan Perez | | 179 | 209 | -30 |
| 2012-05-22 | vs SFN | 43 | L 4-6 | 19-24 | 5 | 30,451 | Shaun Marcum | Matt Cain | Matt Cain | Shaun Marcum | Santiago Casilla | 183 | 215 | -32 |
| 2012-05-23 | vs SFN | 44 | W 8-5 | 20-24 | 5 | 37,691 | Marco Estrada | Barry Zito | Jose Veras | Barry Zito | John Axford | 191 | 220 | -29 |
| 2012-05-25 | @ ARI | 45 | W 7-1 | 21-24 | 5 | 35,478 | Yovani Gallardo | Ian Kennedy | Yovani Gallardo | Ian Kennedy | | 198 | 221 | -23 |
| 2012-05-26 | @ ARI | 46 | L 5-8 | 21-25 | 5 | 30,184 | Zack Greinke | Wade Miley | Wade Miley | Zack Greinke | J.J. Putz | 203 | 229 | -26 |
| 2012-05-27 | @ ARI | 47 | L 3-4 | 21-26 | 5 | 33,481 | Randy Wolf | Daniel Hudson | Bryan Shaw | Jose Veras | J.J. Putz | 206 | 233 | -27 |
| 2012-05-28 | @ LAN | 48 | W 3-2 | 22-26 | 4 | 38,016 | Shaun Marcum | Aaron Harang | Shaun Marcum | Aaron Harang | John Axford | 209 | 235 | -26 |
| 2012-05-29 | @ LAN | 49 | W 2-1 | 23-26 | 4 | 51,137 | Michael Fiers | Nathan Eovaldi | Michael Fiers | Nathan Eovaldi | John Axford | 211 | 236 | -25 |
| 2012-05-30 | @ LAN | 50 | W 6-3 | 24-26 | 4 | 25,509 | Yovani Gallardo | Clayton Kershaw | Yovani Gallardo | Clayton Kershaw | John Axford | 217 | 239 | -22 |
| 2012-05-31 | @ LAN | 51 | W 6-2 | 25-26 | 3 | 26,773 | Zack Greinke | Chad Billingsley | Zack Greinke | Chad Billingsley | | 223 | 241 | -18 |
| 2012-06-01 | vs PIT | 52 | L 2-8 | 25-27 | 3 | 33,055 | Randy Wolf | Kevin Correia | Kevin Correia | Randy Wolf | | 225 | 249 | -24 |
| 2012-06-02 | vs PIT | 53 | W 5-1 | 26-27 | 3 | 39,603 | Shaun Marcum | Erik Bedard | Shaun Marcum | Erik Bedard | | 230 | 250 | -20 |
| 2012-06-03 | vs PIT | 54 | L 5-6 | 26-28 | 3 | 34,334 | Michael Fiers | James McDonald | James McDonald | Michael Fiers | Joel Hanrahan | 235 | 256 | -21 |
| 2012-06-05 | vs CHN | 55 | L 0-10 | 26-29 | 4 | 28,071 | Yovani Gallardo | Ryan Dempster | Ryan Dempster | Yovani Gallardo | | 235 | 266 | -31 |
| 2012-06-06 | vs CHN | 56 | W 8-0 | 27-29 | 3 | 27,112 | Zack Greinke | Paul Maholm | Zack Greinke | Paul Maholm | | 243 | 266 | -23 |
| 2012-06-07 | vs CHN | 57 | W 4-3 | 28-29 | 3 | 30,123 | Randy Wolf | Matt Garza | John Axford | Casey Coleman | | 247 | 269 | -22 |
| 2012-06-08 | vs SDN | 58 | W 9-5 | 29-29 | 3 | 32,759 | Shaun Marcum | Edinson Volquez | Shaun Marcum | Edinson Volquez | | 256 | 274 | -18 |
| 2012-06-09 | vs SDN | 59 | L 2-5 | 29-30 | 3 | 41,604 | Michael Fiers | Andrew Cashner | Ross Ohlendorf | Michael Fiers | Huston Street | 258 | 279 | -21 |
| 2012-06-10 | vs SDN | 60 | W 6-5 | 30-30 | 3 | 43,021 | Yovani Gallardo | Anthony Bass | Yovani Gallardo | Anthony Bass | Jose Veras | 264 | 284 | -20 |
| 2012-06-12 | @ KCA | 61 | L 1-2 | 30-31 | 3 | 24,258 | Zack Greinke | Luis Mendoza | Greg Holland | Francisco Rodriguez | Jonathan Broxton | 265 | 286 | -21 |
| 2012-06-13 | @ KCA | 62 | L 3-4 | 30-32 | 3 | 17,885 | Randy Wolf | Jonathan Sanchez | Tim Collins | Kameron Loe | | 268 | 290 | -22 |
| 2012-06-14 | @ KCA | 63 | L 3-4 | 30-33 | 3 | 21,869 | Shaun Marcum | Luke Hochevar | Tim Collins | John Axford | | 271 | 294 | -23 |
| 2012-06-15 | @ MIN | 64 | W 5-3 | 31-33 | 3 | 37,295 | Yovani Gallardo | Francisco Liriano | Kameron Loe | Matt Capps | John Axford | 276 | 297 | -21 |
| 2012-06-16 | @ MIN | 65 | W 6-2 | 32-33 | 3 | 37,698 | Michael Fiers | Liam Hendriks | Michael Fiers | Liam Hendriks | | 282 | 299 | -17 |
| 2012-06-17 | @ MIN | 66 | L 4-5 | 32-34 | 3 | 39,206 | Zack Greinke | Nick Blackburn | Anthony Swarzak | Tim Dillard | | 286 | 304 | -18 |
| 2012-06-18 | vs TOR | 67 | W 7-6 | 33-34 | 3 | 32,223 | Randy Wolf | Henderson Alvarez | Kameron Loe | Robert Coello | John Axford | 293 | 310 | -17 |
| 2012-06-19 | vs TOR | 68 | W 9-10 | 34-34 | 3 | 36,334 | Tyler Thornburg | Jesse Chavez | Darren Oliver | John Axford | Casey Janssen | 302 | 320 | -18 |
| 2012-06-20 | vs TOR | 69 | W 8-3 | 35-34 | 3 | 33,077 | Yovani Gallardo | Joel Carreno | Yovani Gallardo | Joel Carreno | | 310 | 323 | -13 |
| 2012-06-22 | @ CHA | 70 | W 1-0 | 36-34 | 3 | 22,798 | Zack Greinke | Chris Sale | Zack Greinke | Jesse Crain | John Axford | 311 | 323 | -12 |
| 2012-06-23 | @ CHA | 71 | L 6-8 | 36-35 | 3 | 30,337 | Randy Wolf | Dylan Axelrod | Jesse Crain | Jose Veras | Addison Reed | 317 | 331 | -14 |
| 2012-06-24 | @ CHA | 72 | L 0-1 | 36-36 | 3 | 26,545 | Michael Fiers | Jose Quintana | Brian Bruney | Manny Parra | | 317 | 332 | -15 |
| 2012-06-25 | @ CIN | 73 | L 1-3 | 36-37 | 3 | 34,485 | Yovani Gallardo | Mat Latos | Mat Latos | Yovani Gallardo | | 318 | 335 | -17 |
| 2012-06-26 | @ CIN | 74 | L 3-4 | 36-38 | 3 | 32,986 | Marco Estrada | Bronson Arroyo | Sean Marshall | John Axford | Aroldis Chapman | 321 | 339 | -18 |
| 2012-06-27 | @ CIN | 75 | W 8-4 | 37-38 | 3 | 28,906 | Zack Greinke | Homer Bailey | Zack Greinke | Homer Bailey | | 329 | 343 | -14 |
| 2012-06-29 | vs ARI | 76 | L 3-9 | 37-39 | 3 | 38,030 | Randy Wolf | Ian Kennedy | Ian Kennedy | Randy Wolf | | 332 | 352 | -20 |
| 2012-06-30 | vs ARI | 77 | L 10-2 | 37-40 | 3 | 41,647 | Michael Fiers | Wade Miley | Michael Fiers | Wade Miley | | 342 | 354 | -12 |
| 2012-07-01 | vs ARI | 78 | W 2-1 | 38-40 | 3 | 38,605 | Yovani Gallardo | Josh Collmenter | John Axford | Patrick Corbin | | 344 | 355 | -11 |
| 2012-07-02 | vs MIA | 79 | W 6-5 | 39-40 | 3 | 28,674 | Zack Greinke | Carlos Zambrano | Francisco Rodriguez | Ryan Webb | John Axford | 350 | 360 | -10 |
| 2012-07-03 | vs MIA | 80 | W 13-12 | 40-40 | 3 | 33,178 | Marco Estrada | Anibal Sanchez | Livan Hernandez | Heath Bell | | 363 | 372 | -9 |
| 2012-07-04 | vs MIA | 81 | L 6-7 | 40-41 | 3 | 31,910 | Randy Wolf | Josh Johnson | Wade LeBlanc | Manny Parra | Heath Bell | 369 | 379 | -10 |
| 2012-07-05 | vs MIA | 82 | L 0-4 | 40-42 | 3 | 27,443 | Michael Fiers | Mark Buehrle | Mark Buehrle | Michael Fiers | | 369 | 383 | -14 |
| 2012-07-06 | @ HOU | 83 | W 7-1 | 41-42 | 3 | 23,430 | Yovani Gallardo | J.A. Happ | Yovani Gallardo | J.A. Happ | | 376 | 384 | -8 |
| 2012-07-07 | @ HOU | 84 | L 3-6 | 41-43 | 3 | 23,027 | Zack Greinke | Wandy Rodriguez | Wandy Rodriguez | Zack Greinke | Brett Myers | 379 | 390 | -11 |
| 2012-07-08 | @ HOU | 85 | W 5-3 | 42-43 | 3 | 16,966 | Zack Greinke | Jordan Lyles | Manny Parra | Fernando Rodriguez | John Axford | 384 | 393 | -9 |
| 2012-07-13 | vs PIT | 86 | L 10-7 | 42-44 | 3 | 35,025 | Zack Greinke | James McDonald | Francisco Rodriguez | Tony Watson | | 394 | 400 | -6 |
| 2012-07-14 | vs PIT | 87 | L 4-6 | 42-45 | 3 | 42,029 | Marco Estrada | Kevin Correia | Kevin Correia | Kameron Loe | Joel Hanrahan | 398 | 406 | -8 |
| 2012-07-15 | vs PIT | 88 | W 4-1 | 43-45 | 3 | 35,430 | Yovani Gallardo | A.J. Burnett | Yovani Gallardo | A.J. Burnett | John Axford | 402 | 407 | -5 |
| 2012-07-16 | vs SLN | 89 | L 2-3 | 43-46 | 3 | 30,128 | Michael Fiers | Lance Lynn | Jason Motte | John Axford | | 404 | 410 | -6 |
| 2012-07-17 | vs SLN | 90 | W 3-2 | 44-46 | 3 | 30,491 | Randy Wolf | Joe Kelly | Randy Wolf | Joe Kelly | Francisco Rodriguez | 407 | 412 | -5 |
| 2012-07-18 | vs SLN | 91 | W 4-3 | 45-46 | 3 | 37,753 | Tyler Thornburg | Adam Wainwright | John Axford | Adam Wainwright | Francisco Rodriguez | 411 | 415 | -4 |
| 2012-07-20 | @ CIN | 92 | L 1-3 | 45-47 | 3 | 30,247 | Marco Estrada | Homer Bailey | Homer Bailey | Marco Estrada | Aroldis Chapman | 412 | 418 | -6 |
| 2012-07-21 | @ CIN | 93 | L 2-6 | 45-48 | 3 | 40,090 | Yovani Gallardo | Bronson Arroyo | Bronson Arroyo | Yovani Gallardo | | 414 | 424 | -10 |
| 2012-07-22 | @ CIN | 94 | L 1-2 | 45-49 | 3 | 32,884 | Michael Fiers | Johnny Cueto | Johnny Cueto | Michael Fiers | Aroldis Chapman | 415 | 426 | -11 |
| 2012-07-23 | @ PHI | 95 | L 6-7 | 45-50 | 3 | 43,717 | Randy Wolf | Roy Halladay | Joe Savery | Francisco Rodriguez | | 421 | 433 | -12 |
| 2012-07-24 | @ PHI | 96 | L 6-7 | 45-51 | 4 | 43,745 | Zack Greinke | Cliff Lee | Michael Schwimer | Kameron Loe | Jonathan Papelbon | 427 | 440 | -13 |
| 2012-07-25 | @ PHI | 97 | L 6-7 | 45-52 | 4 | 44,715 | Marco Estrada | Vance Worley | Michael Schwimer | Francisco Rodriguez | | 433 | 447 | -14 |
| 2012-07-26 | vs WAS | 98 | L 2-8 | 45-53 | 4 | 33,176 | Yovani Gallardo | Edwin Jackson | Edwin Jackson | Yovani Gallardo | | 435 | 455 | -20 |
| 2012-07-27 | vs WAS | 99 | W 6-0 | 46-53 | 4 | 35,858 | Michael Fiers | Ross Detwiler | Michael Fiers | Ross Detwiler | | 441 | 455 | -14 |
| 2012-07-28 | vs WAS | 100 | L 1-4 | 46-54 | 4 | 41,890 | Randy Wolf | Jordan Zimmermann | Jordan Zimmermann | Randy Wolf | Tyler Clippard | 442 | 459 | -17 |
| 2012-07-29 | vs WAS | 101 | L 10-11 | 46-55 | 4 | 44,663 | Mark Rogers | Gio Gonzalez | Craig Stammen | Jose Veras | Tyler Clippard | 452 | 470 | -18 |
| 2012-07-30 | vs HOU | 102 | W 8-7 | 47-55 | 4 | 28,131 | Marco Estrada | Bud Norris | Livan Hernandez | Francisco Cordero | John Axford | 460 | 477 | -17 |
| 2012-07-31 | vs HOU | 103 | W 10-1 | 48-55 | 4 | 30,011 | Yovani Gallardo | Dallas Keuchel | Yovani Gallardo | Dallas Keuchel | | 470 | 478 | -8 |
| 2012-08-01 | vs HOU | 104 | L 13-4 | 48-56 | 4 | 32,217 | Michael Fiers | Jordan Lyles | Michael Fiers | Jordan Lyles | | 483 | 482 | 1 |
| 2012-08-03 | @ SLN | 105 | L 3-9 | 48-57 | 4 | 41,505 | Randy Wolf | Joe Kelly | Joe Kelly | Randy Wolf | | 486 | 491 | -5 |
| 2012-08-04 | @ SLN | 106 | L 1-6 | 48-58 | 4 | 42,036 | Mark Rogers | Adam Wainwright | Adam Wainwright | Mark Rogers | | 487 | 497 | -10 |
| 2012-08-05 | @ SLN | 107 | L 0-3 | 48-59 | 4 | 40,274 | Marco Estrada | Kyle Lohse | Kyle Lohse | Marco Estrada | Jason Motte | 487 | 500 | -13 |
| 2012-08-06 | vs CIN | 108 | W 6-3 | 49-59 | 4 | 31,319 | Yovani Gallardo | Bronson Arroyo | Yovani Gallardo | Bronson Arroyo | John Axford | 493 | 503 | -10 |
| 2012-08-07 | vs CIN | 109 | W 3-1 | 50-59 | 4 | 41,213 | Michael Fiers | Johnny Cueto | Michael Fiers | Johnny Cueto | Jim Henderson | 496 | 504 | -8 |
| 2012-08-08 | vs CIN | 110 | W 3-2 | 51-59 | 4 | 33,788 | Randy Wolf | Mat Latos | John Axford | Jonathan Broxton | Jim Henderson | 499 | 506 | -7 |
| 2012-08-10 | @ HOU | 111 | L 3-4 | 51-60 | 4 | 21,025 | Mark Rogers | Bud Norris | Wilton Lopez | John Axford | | 502 | 510 | -8 |
| 2012-08-11 | @ HOU | 112 | L 5-6 | 51-61 | 4 | 17,942 | Marco Estrada | Dallas Keuchel | Wilton Lopez | Jim Henderson | | 507 | 516 | -9 |
| 2012-08-12 | @ HOU | 113 | W 5-3 | 52-61 | 4 | 19,235 | Yovani Gallardo | Jordan Lyles | Yovani Gallardo | Jordan Lyles | Kameron Loe | 512 | 519 | -7 |
| 2012-08-13 | @ COL | 114 | L 6-9 | 52-62 | 4 | 26,821 | Michael Fiers | Jeff Francis | Jeff Francis | Michael Fiers | | 518 | 528 | -10 |
| 2012-08-14 | @ COL | 115 | L 6-8 | 52-63 | 4 | 28,036 | Randy Wolf | Tyler Chatwood | Tyler Chatwood | Randy Wolf | Rafael Betancourt | 524 | 536 | -12 |
| 2012-08-15 | @ COL | 116 | L 6-7 | 52-64 | 4 | 23,411 | Mark Rogers | Guillermo Moscoso | Will Harris | Jim Henderson | | 530 | 543 | -13 |
| 2012-08-16 | vs PHI | 117 | W 7-4 | 53-64 | 4 | 30,117 | Marco Estrada | Cliff Lee | Livan Hernandez | Josh Lindblom | Jim Henderson | 537 | 547 | -10 |
| 2012-08-17 | vs PHI | 118 | W 6-2 | 54-64 | 4 | 39,163 | Yovani Gallardo | Vance Worley | Yovani Gallardo | Vance Worley | | 543 | 549 | -6 |
| 2012-08-18 | vs PHI | 119 | L 3-4 | 54-65 | 5 | 43,386 | Michael Fiers | Cole Hamels | Cole Hamels | Michael Fiers | Jonathan Papelbon | 546 | 553 | -7 |
| 2012-08-19 | vs PHI | 120 | L 0-8 | 54-66 | 4 | 42,224 | Randy Wolf | Kyle Kendrick | Kyle Kendrick | Randy Wolf | | 546 | 561 | -15 |
| 2012-08-20 | vs CHN | 121 | W 9-5 | 55-66 | 4 | 28,776 | Mark Rogers | Justin Germano | Mark Rogers | Justin Germano | | 555 | 566 | -11 |
| 2012-08-21 | vs CHN | 122 | W 5-2 | 56-66 | 4 | 29,179 | Marco Estrada | Chris Rusin | Marco Estrada | Chris Rusin | John Axford | 560 | 568 | -8 |
| 2012-08-22 | vs CHN | 123 | W 3-2 | 57-66 | 4 | 30,743 | Yovani Gallardo | Travis Wood | Yovani Gallardo | Travis Wood | John Axford | 563 | 570 | -7 |
| 2012-08-24 | @ PIT | 124 | W 6-5 | 58-66 | 4 | 37,197 | Michael Fiers | Wandy Rodriguez | Michael Fiers | Wandy Rodriguez | Kameron Loe | 569 | 575 | -6 |
| 2012-08-25 | @ PIT | 125 | L 0-4 | 58-67 | 4 | 37,460 | Shaun Marcum | Jeff Karstens | Jeff Karstens | Shaun Marcum | | 569 | 579 | -10 |
| 2012-08-26 | @ PIT | 126 | W 7-0 | 59-67 | 4 | 36,626 | Mark Rogers | Erik Bedard | Mark Rogers | Erik Bedard | | 576 | 579 | -3 |
| 2012-08-27 | @ CHN | 127 | L 15-4 | 59-68 | 4 | 32,541 | Marco Estrada | Justin Germano | Marco Estrada | Justin Germano | | 591 | 583 | 8 |
| 2012-08-28 | @ CHN | 128 | W 4-1 | 60-68 | 4 | 30,017 | Yovani Gallardo | Travis Wood | Yovani Gallardo | Travis Wood | John Axford | 595 | 584 | 11 |
| 2012-08-29 | @ CHN | 129 | W 3-1 | 61-68 | 4 | 33,271 | Michael Fiers | Jeff Samardzija | Michael Fiers | Jeff Samardzija | John Axford | 598 | 585 | 13 |
| 2012-08-30 | @ CHN | 130 | L 11-12 | 61-69 | 4 | 28,859 | Shaun Marcum | Brooks Raley | Carlos Marmol | Francisco Rodriguez | | 609 | 597 | 12 |
| 2012-08-31 | vs PIT | 131 | W 9-3 | 62-69 | 4 | 33,877 | Mark Rogers | Jeff Karstens | Mark Rogers | Jeff Karstens | | 618 | 600 | 18 |
| 2012-09-01 | vs PIT | 132 | W 3-2 | 63-69 | 4 | 32,060 | Marco Estrada | A.J. Burnett | John Axford | Joel Hanrahan | | 621 | 602 | 19 |
| 2012-09-02 | vs PIT | 133 | L 12-8 | 63-70 | 4 | 32,728 | Yovani Gallardo | James McDonald | Kameron Loe | James McDonald | John Axford | 633 | 610 | 23 |
| 2012-09-03 | @ MIA | 134 | L 3-7 | 63-71 | 4 | 22,391 | Michael Fiers | Ricky Nolasco | Ricky Nolasco | Michael Fiers | Steve Cishek | 636 | 617 | 19 |
| 2012-09-04 | @ MIA | 135 | W 8-4 | 64-71 | 4 | 23,403 | Shaun Marcum | Wade LeBlanc | Kameron Loe | Michael Dunn | John Axford | 644 | 621 | 23 |
| 2012-09-05 | @ MIA | 136 | W 8-5 | 65-71 | 4 | 22,288 | Wily Peralta | Nathan Eovaldi | Wily Peralta | Nathan Eovaldi | John Axford | 652 | 626 | 26 |
| 2012-09-06 | @ MIA | 137 | L 2-6 | 65-72 | 4 | 18,707 | Marco Estrada | Josh Johnson | Josh Johnson | Marco Estrada | | 654 | 632 | 22 |
| 2012-09-07 | @ SLN | 138 | W 5-4 | 66-72 | 3 | 38,648 | Yovani Gallardo | Kyle Lohse | Brandon Kintzler | Lance Lynn | John Axford | 659 | 636 | 23 |
| 2012-09-08 | @ SLN | 139 | W 6-3 | 67-72 | 3 | 40,422 | Michael Fiers | Jake Westbrook | Michael Fiers | Jake Westbrook | John Axford | 665 | 639 | 26 |
| 2012-09-09 | @ SLN | 140 | L 4-5 | 67-73 | 3 | 39,919 | Shaun Marcum | Joe Kelly | Lance Lynn | Kameron Loe | | 669 | 644 | 25 |
| 2012-09-10 | vs ATL | 141 | W 4-1 | 68-73 | 3 | 34,395 | Wily Peralta | Mike Minor | Jose Veras | Jonny Venters | John Axford | 673 | 645 | 28 |
| 2012-09-11 | vs ATL | 142 | W 5-0 | 69-73 | 3 | 27,382 | Marco Estrada | Tim Hudson | Marco Estrada | Tim Hudson | | 678 | 645 | 33 |
| 2012-09-12 | vs ATL | 143 | W 8-2 | 70-73 | 3 | 37,847 | Yovani Gallardo | Paul Maholm | Yovani Gallardo | Paul Maholm | | 686 | 647 | 39 |
| 2012-09-14 | vs NYN | 144 | L 3-7 | 70-74 | 3 | 38,216 | Michael Fiers | Jonathon Niese | Jonathon Niese | Michael Fiers | | 689 | 654 | 35 |
| 2012-09-15 | vs NYN | 145 | W 9-6 | 71-74 | 3 | 38,108 | Shaun Marcum | Jenrry Mejia | Brandon Kintzler | Jenrry Mejia | | 698 | 660 | 38 |
| 2012-09-16 | vs NYN | 146 | W 3-0 | 72-74 | 3 | 38,677 | Wily Peralta | Chris Young | Wily Peralta | Chris Young | John Axford | 701 | 660 | 41 |
| 2012-09-18 | @ PIT | 147 | W 6-0 | 73-74 | 3 | 15,492 | Yovani Gallardo | A.J. Burnett | Yovani Gallardo | A.J. Burnett | | 707 | 660 | 47 |
| 2012-09-19 | @ PIT | 148 | W 3-1 | 74-74 | 3 | 15,337 | Marco Estrada | Kyle McPherson | Marco Estrada | Kyle McPherson | John Axford | 710 | 661 | 49 |
| 2012-09-20 | @ PIT | 149 | W 9-7 | 75-74 | 3 | 14,697 | Michael Fiers | Wandy Rodriguez | Manny Parra | Chris Resop | John Axford | 719 | 668 | 51 |
| 2012-09-21 | @ WAS | 150 | W 4-2 | 76-74 | 2 | 30,382 | Shaun Marcum | Edwin Jackson | Jose Veras | Tyler Clippard | John Axford | 723 | 670 | 53 |
| 2012-09-22 | @ WAS | 151 | W 4-10 | 77-74 | 2 | 40,493 | Wily Peralta | Gio Gonzalez | Gio Gonzalez | Wily Peralta | | 727 | 680 | 47 |
| 2012-09-23 | @ WAS | 152 | W 6-2 | 78-74 | 2 | 33,111 | Yovani Gallardo | Chien-Ming Wang | Brandon Kintzler | Ryan Mattheus | John Axford | 733 | 682 | 51 |
| 2012-09-24 | @ WAS | 153 | W 2-12 | 79-74 | 2 | 25,302 | Marco Estrada | Jordan Zimmermann | Jordan Zimmermann | Marco Estrada | | 735 | 694 | 41 |
| 2012-09-25 | @ CIN | 154 | L 2-4 | 79-75 | 2 | 18,155 | Michael Fiers | Johnny Cueto | Johnny Cueto | Michael Fiers | Aroldis Chapman | 737 | 698 | 39 |
| 2012-09-26 | @ CIN | 155 | W 8-1 | 80-75 | 2 | 20,570 | Shaun Marcum | Bronson Arroyo | Shaun Marcum | Bronson Arroyo | | 745 | 699 | 46 |
| 2012-09-27 | @ CIN | 156 | L 1-2 | 80-76 | 2 | 23,411 | Wily Peralta | Mat Latos | Jonathan Broxton | John Axford | | 746 | 701 | 45 |
| 2012-09-28 | vs HOU | 157 | L 6-7 | 80-77 | 2 | 41,716 | Yovani Gallardo | Edgar Gonzalez | Edgar Gonzalez | Yovani Gallardo | Wilton Lopez | 752 | 708 | 44 |
| 2012-09-29 | vs HOU | 158 | W 9-5 | 81-77 | 2 | 34,294 | Marco Estrada | Dallas Keuchel | Marco Estrada | Dallas Keuchel | | 761 | 713 | 48 |
| 2012-09-30 | vs HOU | 159 | L 0-7 | 81-78 | 2 | 38,443 | Michael Fiers | Jordan Lyles | Jordan Lyles | Michael Fiers | | 761 | 720 | 41 |
| 2012-10-01 | vs SDN | 160 | W 5-3 | 82-78 | 2 | 30,398 | Shaun Marcum | Clayton Richard | Shaun Marcum | Clayton Richard | John Axford | 766 | 723 | 43 |
| 2012-10-02 | vs SDN | 161 | W 4-3 | 83-78 | 2 | 30,714 | Tyler Thornburg | Anthony Bass | Jim Henderson | Anthony Bass | John Axford | 770 | 726 | 44 |
| 2012-10-03 | vs SDN | 162 | L 6-7 | 83-79 | 2 | 34,451 | Josh Stinson | Andrew Werner | Tom Layne | Jim Henderson | Luke Gregerson | 776 | 733 | 43 |