| 2012-04-05 | vs MIA | 1 | W 4-0 | 1-0 | 1 | 42,956 | Johnny Cueto | Mark Buehrle | Johnny Cueto | Mark Buehrle | | 4 | 0 | 4 |
| 2012-04-07 | vs MIA | 2 | L 3-8 | 1-1 | 2 | 41,662 | Mat Latos | Ricky Nolasco | Ricky Nolasco | Mat Latos | | 7 | 8 | -1 |
| 2012-04-08 | vs MIA | 3 | W 6-5 | 2-1 | 1 | 23,539 | Bronson Arroyo | Carlos Zambrano | Aroldis Chapman | Heath Bell | | 13 | 13 | 0 |
| 2012-04-09 | vs SLN | 4 | L 1-7 | 2-2 | 5 | 16,909 | Homer Bailey | Jake Westbrook | Jake Westbrook | Homer Bailey | | 14 | 20 | -6 |
| 2012-04-10 | vs SLN | 5 | L 1-3 | 2-3 | 5 | 17,110 | Mike Leake | Kyle Lohse | Kyle Lohse | Mike Leake | Jason Motte | 15 | 23 | -8 |
| 2012-04-11 | vs SLN | 6 | W 4-3 | 3-3 | 3 | 20,672 | Johnny Cueto | Jaime Garcia | Aroldis Chapman | Marc Rzepczynski | | 19 | 26 | -7 |
| 2012-04-12 | @ WAS | 7 | L 2-3 | 3-4 | 4 | 40,907 | Mat Latos | Gio Gonzalez | Craig Stammen | Alfredo Simon | | 21 | 29 | -8 |
| 2012-04-13 | @ WAS | 8 | L 1-2 | 3-5 | 5 | 26,959 | Bronson Arroyo | Jordan Zimmermann | Craig Stammen | Sean Marshall | | 22 | 31 | -9 |
| 2012-04-14 | @ WAS | 9 | L 1-4 | 3-6 | 5 | 35,489 | Homer Bailey | Edwin Jackson | Edwin Jackson | Homer Bailey | | 23 | 35 | -12 |
| 2012-04-15 | @ WAS | 10 | W 8-5 | 4-6 | 5 | 25,679 | Mike Leake | Ross Detwiler | Jose Arredondo | Tyler Clippard | Sean Marshall | 31 | 40 | -9 |
| 2012-04-17 | @ SLN | 11 | L 1-2 | 4-7 | 4 | 35,562 | Johnny Cueto | Kyle Lohse | Jason Motte | Sam LeCure | | 32 | 42 | -10 |
| 2012-04-18 | @ SLN | 12 | L 1-11 | 4-8 | 5 | 35,907 | Mat Latos | Jaime Garcia | Jaime Garcia | Mat Latos | | 33 | 53 | -20 |
| 2012-04-19 | @ SLN | 13 | W 6-3 | 5-8 | 4 | 40,049 | Bronson Arroyo | Adam Wainwright | Bronson Arroyo | Adam Wainwright | Sean Marshall | 39 | 56 | -17 |
| 2012-04-20 | @ CHN | 14 | W 9-4 | 6-8 | 3 | 37,782 | Homer Bailey | Chris Volstad | Homer Bailey | Chris Volstad | | 48 | 60 | -12 |
| 2012-04-21 | @ CHN | 15 | L 1-6 | 6-9 | 4 | 38,405 | Mike Leake | Paul Maholm | Paul Maholm | Mike Leake | | 49 | 66 | -17 |
| 2012-04-22 | @ CHN | 16 | W 4-3 | 7-9 | 3 | 35,801 | Johnny Cueto | Randy Wells | Johnny Cueto | Rodrigo Lopez | Sean Marshall | 53 | 69 | -16 |
| 2012-04-24 | vs SFN | 17 | W 9-2 | 8-9 | 3 | 19,051 | Mat Latos | Matt Cain | Mat Latos | Matt Cain | | 62 | 71 | -9 |
| 2012-04-25 | vs SFN | 18 | W 4-2 | 9-9 | 3 | 17,115 | Bronson Arroyo | Barry Zito | Jose Arredondo | Clay Hensley | Sean Marshall | 66 | 73 | -7 |
| 2012-04-26 | vs SFN | 19 | L 5-6 | 9-10 | 3 | 17,317 | Homer Bailey | Ryan Vogelsong | Javier Lopez | Sean Marshall | Santiago Casilla | 71 | 79 | -8 |
| 2012-04-27 | vs HOU | 20 | L 4-6 | 9-11 | 3 | 29,486 | Mike Leake | Wandy Rodriguez | Wandy Rodriguez | Mike Leake | Brett Myers | 75 | 85 | -10 |
| 2012-04-28 | vs HOU | 21 | W 6-0 | 10-11 | 3 | 32,971 | Johnny Cueto | Lucas Harrell | Johnny Cueto | Lucas Harrell | | 81 | 85 | -4 |
| 2012-04-29 | vs HOU | 22 | W 6-5 | 11-11 | 3 | 31,086 | Mat Latos | Jordan Lyles | Logan Ondrusek | Fernando Rodriguez | Sean Marshall | 87 | 90 | -3 |
| 2012-05-02 | vs CHN | 23 | L 1-3 | 11-12 | 4 | 16,868 | Bronson Arroyo | Jeff Samardzija | Jeff Samardzija | Bronson Arroyo | Carlos Marmol | 88 | 93 | -5 |
| 2012-05-03 | vs CHN | 24 | W 4-3 | 12-12 | 3 | 23,288 | Homer Bailey | Ryan Dempster | Logan Ondrusek | Rafael Dolis | | 92 | 96 | -4 |
| 2012-05-04 | @ PIT | 25 | W 6-1 | 13-12 | 2 | 20,445 | Johnny Cueto | Kevin Correia | Johnny Cueto | Kevin Correia | | 98 | 97 | 1 |
| 2012-05-05 | @ PIT | 26 | L 2-3 | 13-13 | 3 | 33,019 | Mike Leake | James McDonald | James McDonald | Mike Leake | Joel Hanrahan | 100 | 100 | 0 |
| 2012-05-06 | @ PIT | 27 | W 5-0 | 14-13 | 1 | 20,042 | Mat Latos | Charlie Morton | Mat Latos | Charlie Morton | | 105 | 100 | 5 |
| 2012-05-07 | @ MIL | 28 | W 6-1 | 15-13 | 1 | 27,157 | Bronson Arroyo | Marco Estrada | Bronson Arroyo | Marco Estrada | | 111 | 101 | 10 |
| 2012-05-08 | @ MIL | 29 | L 3-8 | 15-14 | 1 | 28,108 | Homer Bailey | Yovani Gallardo | Yovani Gallardo | Homer Bailey | | 114 | 109 | 5 |
| 2012-05-09 | @ MIL | 30 | W 2-1 | 16-14 | 1 | 27,090 | Johnny Cueto | Zack Greinke | Aroldis Chapman | John Axford | Logan Ondrusek | 116 | 110 | 6 |
| 2012-05-11 | vs WAS | 31 | L 3-7 | 16-15 | 1 | 37,255 | Mike Leake | Gio Gonzalez | Gio Gonzalez | Mike Leake | | 119 | 117 | 2 |
| 2012-05-12 | vs WAS | 32 | L 1-2 | 16-16 | 3 | 42,294 | Mat Latos | Jordan Zimmermann | Jordan Zimmermann | Jose Arredondo | Henry Rodriguez | 120 | 119 | 1 |
| 2012-05-13 | vs WAS | 33 | W 9-6 | 17-16 | 2 | 28,361 | Bronson Arroyo | Edwin Jackson | Sean Marshall | Henry Rodriguez | | 129 | 125 | 4 |
| 2012-05-14 | @ ATL | 34 | W 3-1 | 18-16 | 2 | 19,697 | Homer Bailey | Randall Delgado | Logan Ondrusek | Jonny Venters | Sean Marshall | 132 | 126 | 6 |
| 2012-05-15 | @ ATL | 35 | L 2-6 | 18-17 | 2 | 21,530 | Johnny Cueto | Tim Hudson | Tim Hudson | Johnny Cueto | | 134 | 132 | 2 |
| 2012-05-16 | @ NYN | 36 | W 6-3 | 19-17 | 1 | 22,659 | Mike Leake | Johan Santana | Jose Arredondo | Jon Rauch | Sean Marshall | 140 | 135 | 5 |
| 2012-05-17 | @ NYN | 37 | L 4-9 | 19-18 | 2 | 29,943 | Mat Latos | R.A. Dickey | Bobby Parnell | Logan Ondrusek | | 144 | 144 | 0 |
| 2012-05-18 | @ NYA | 38 | L 0-4 | 19-19 | 2 | 42,015 | Bronson Arroyo | Andy Pettitte | Andy Pettitte | Bronson Arroyo | | 144 | 148 | -4 |
| 2012-05-19 | @ NYA | 39 | W 6-5 | 20-19 | 2 | 45,302 | Homer Bailey | Ivan Nova | Homer Bailey | Ivan Nova | Jose Arredondo | 150 | 153 | -3 |
| 2012-05-20 | @ NYA | 40 | W 5-2 | 21-19 | 1 | 45,622 | Johnny Cueto | CC Sabathia | Johnny Cueto | CC Sabathia | Aroldis Chapman | 155 | 155 | 0 |
| 2012-05-21 | vs ATL | 41 | W 4-1 | 22-19 | 1 | 17,606 | Mike Leake | Mike Minor | Mike Leake | Mike Minor | Sean Marshall | 159 | 156 | 3 |
| 2012-05-22 | vs ATL | 42 | W 4-3 | 23-19 | 1 | 26,438 | Mat Latos | Brandon Beachy | Mat Latos | Brandon Beachy | Aroldis Chapman | 163 | 159 | 4 |
| 2012-05-23 | vs ATL | 43 | W 2-1 | 24-19 | 1 | 20,411 | Bronson Arroyo | Tommy Hanson | Aroldis Chapman | Cristhian Martinez | | 165 | 160 | 5 |
| 2012-05-24 | vs ATL | 44 | W 6-3 | 25-19 | 1 | 23,312 | Homer Bailey | Randall Delgado | Homer Bailey | Randall Delgado | Logan Ondrusek | 171 | 163 | 8 |
| 2012-05-25 | vs COL | 45 | L 3-6 | 25-20 | 1 | 29,597 | Johnny Cueto | Christian Friedrich | Christian Friedrich | Johnny Cueto | Rafael Betancourt | 174 | 169 | 5 |
| 2012-05-26 | vs COL | 46 | L 10-3 | 25-21 | 1 | 35,314 | Mike Leake | Jeremy Guthrie | J.J. Hoover | Jeremy Guthrie | | 184 | 172 | 12 |
| 2012-05-27 | vs COL | 47 | W 7-5 | 26-21 | 1 | 29,368 | Mat Latos | Jamie Moyer | Mat Latos | Jamie Moyer | Aroldis Chapman | 191 | 177 | 14 |
| 2012-05-28 | @ PIT | 48 | L 1-4 | 26-22 | 1 | 14,792 | Bronson Arroyo | James McDonald | James McDonald | Bronson Arroyo | Joel Hanrahan | 192 | 181 | 11 |
| 2012-05-29 | @ PIT | 49 | W 8-1 | 27-22 | 1 | 12,077 | Homer Bailey | Charlie Morton | Homer Bailey | Charlie Morton | | 200 | 182 | 18 |
| 2012-05-30 | @ PIT | 50 | L 1-2 | 27-23 | 1 | 16,782 | Johnny Cueto | A.J. Burnett | A.J. Burnett | Johnny Cueto | Joel Hanrahan | 201 | 184 | 17 |
| 2012-06-01 | @ HOU | 51 | W 4-1 | 28-23 | 1 | 21,464 | Mike Leake | J.A. Happ | Mike Leake | J.A. Happ | Aroldis Chapman | 205 | 185 | 20 |
| 2012-06-02 | @ HOU | 52 | L 12-9 | 28-24 | 1 | 22,991 | Mat Latos | Wandy Rodriguez | Sam LeCure | Fernando Rodriguez | Aroldis Chapman | 217 | 194 | 23 |
| 2012-06-03 | @ HOU | 53 | L 3-5 | 28-25 | 1 | 19,914 | Bronson Arroyo | Jordan Lyles | Jordan Lyles | Bronson Arroyo | Brett Myers | 220 | 199 | 21 |
| 2012-06-05 | vs PIT | 54 | L 4-8 | 28-26 | 2 | 19,906 | Homer Bailey | A.J. Burnett | A.J. Burnett | Homer Bailey | Joel Hanrahan | 224 | 207 | 17 |
| 2012-06-06 | vs PIT | 55 | W 5-4 | 29-26 | 1 | 16,859 | Johnny Cueto | Brad Lincoln | Johnny Cueto | Brad Lincoln | Aroldis Chapman | 229 | 211 | 18 |
| 2012-06-07 | vs PIT | 56 | L 4-5 | 29-27 | 2 | 23,106 | Mike Leake | Kevin Correia | Joel Hanrahan | Aroldis Chapman | Chris Resop | 233 | 216 | 17 |
| 2012-06-08 | vs DET | 57 | W 6-5 | 30-27 | 2 | 38,563 | Mat Latos | Rick Porcello | Sam LeCure | Phil Coke | | 239 | 221 | 18 |
| 2012-06-09 | vs DET | 58 | L 2-3 | 30-28 | 2 | 42,443 | Bronson Arroyo | Justin Verlander | Brayan Villarreal | Sean Marshall | Jose Valverde | 241 | 224 | 17 |
| 2012-06-10 | vs DET | 59 | L 6-7 | 30-29 | 2 | 34,056 | Homer Bailey | Drew Smyly | Brayan Villarreal | Aroldis Chapman | Jose Valverde | 247 | 231 | 16 |
| 2012-06-12 | vs CLE | 60 | W 7-1 | 31-29 | 2 | 24,758 | Johnny Cueto | Jeanmar Gomez | Johnny Cueto | Jeanmar Gomez | | 254 | 232 | 22 |
| 2012-06-13 | vs CLE | 61 | W 5-3 | 32-29 | 2 | 27,428 | Mat Latos | Derek Lowe | Mat Latos | Derek Lowe | Aroldis Chapman | 259 | 235 | 24 |
| 2012-06-14 | vs CLE | 62 | L 12-5 | 32-30 | 2 | 34,193 | Mike Leake | Josh Tomlin | Jose Arredondo | Josh Tomlin | | 271 | 240 | 31 |
| 2012-06-15 | @ NYN | 63 | W 7-3 | 33-30 | 2 | 34,716 | Bronson Arroyo | Dillon Gee | Bronson Arroyo | Dillon Gee | | 278 | 243 | 35 |
| 2012-06-16 | @ NYN | 64 | W 4-1 | 34-30 | 2 | 27,988 | Homer Bailey | Jonathon Niese | Homer Bailey | Jonathon Niese | Aroldis Chapman | 282 | 244 | 38 |
| 2012-06-17 | @ NYN | 65 | W 3-1 | 35-30 | 2 | 40,134 | Johnny Cueto | Chris Young | Johnny Cueto | Chris Young | Sean Marshall | 285 | 245 | 40 |
| 2012-06-18 | @ CLE | 66 | W 9-10 | 36-30 | 2 | 19,948 | Mat Latos | Derek Lowe | Joe Smith | Sam LeCure | Chris Perez | 294 | 255 | 39 |
| 2012-06-19 | @ CLE | 67 | L 2-3 | 36-31 | 2 | 17,213 | Mike Leake | Josh Tomlin | Nick Hagadone | Aroldis Chapman | | 296 | 258 | 38 |
| 2012-06-20 | @ CLE | 68 | L 1-8 | 36-32 | 2 | 23,544 | Bronson Arroyo | Justin Masterson | Justin Masterson | Bronson Arroyo | | 297 | 266 | 31 |
| 2012-06-22 | vs MIN | 69 | L 4-5 | 36-33 | 2 | 33,531 | Homer Bailey | Nick Blackburn | Nick Blackburn | Homer Bailey | Glen Perkins | 301 | 271 | 30 |
| 2012-06-23 | vs MIN | 70 | W 6-0 | 37-33 | 2 | 41,750 | Johnny Cueto | Brian Duensing | Johnny Cueto | Brian Duensing | | 307 | 271 | 36 |
| 2012-06-24 | vs MIN | 71 | L 3-4 | 37-34 | 2 | 34,513 | Mike Leake | Scott Diamond | Scott Diamond | Aroldis Chapman | Jared Burton | 310 | 275 | 35 |
| 2012-06-25 | vs MIL | 72 | W 3-1 | 38-34 | 2 | 34,485 | Mat Latos | Yovani Gallardo | Mat Latos | Yovani Gallardo | | 313 | 276 | 37 |
| 2012-06-26 | vs MIL | 73 | W 4-3 | 39-34 | 2 | 32,986 | Bronson Arroyo | Marco Estrada | Sean Marshall | John Axford | Aroldis Chapman | 317 | 279 | 38 |
| 2012-06-27 | vs MIL | 74 | L 4-8 | 39-35 | 2 | 28,906 | Homer Bailey | Zack Greinke | Zack Greinke | Homer Bailey | | 321 | 287 | 34 |
| 2012-06-28 | @ SFN | 75 | L 0-5 | 39-36 | 2 | 41,626 | Johnny Cueto | Madison Bumgarner | Madison Bumgarner | Johnny Cueto | | 321 | 292 | 29 |
| 2012-06-29 | @ SFN | 76 | W 5-1 | 40-36 | 2 | 41,960 | Mike Leake | Matt Cain | Mike Leake | Matt Cain | | 326 | 293 | 33 |
| 2012-06-30 | @ SFN | 77 | W 2-1 | 41-36 | 2 | 42,135 | Mat Latos | Barry Zito | Mat Latos | Barry Zito | | 328 | 294 | 34 |
| 2012-07-01 | @ SFN | 78 | L 3-4 | 41-37 | 2 | 42,039 | Bronson Arroyo | Ryan Vogelsong | Santiago Casilla | Jose Arredondo | | 331 | 298 | 33 |
| 2012-07-02 | @ LAN | 79 | W 8-2 | 42-37 | 1 | 34,493 | Homer Bailey | Chad Billingsley | Homer Bailey | Chad Billingsley | | 339 | 300 | 39 |
| 2012-07-03 | @ LAN | 80 | L 1-3 | 42-38 | 2 | 33,884 | Johnny Cueto | Chris Capuano | Scott Elbert | Johnny Cueto | Kenley Jansen | 340 | 303 | 37 |
| 2012-07-04 | @ LAN | 81 | L 1-4 | 42-39 | 2 | 53,570 | Mike Leake | Aaron Harang | Aaron Harang | Mike Leake | Kenley Jansen | 341 | 307 | 34 |
| 2012-07-05 | @ SDN | 82 | L 1-2 | 42-40 | 2 | 25,181 | Mat Latos | Edinson Volquez | Huston Street | Logan Ondrusek | | 342 | 309 | 33 |
| 2012-07-06 | @ SDN | 83 | W 6-0 | 43-40 | 2 | 26,016 | Bronson Arroyo | Kip Wells | Bronson Arroyo | Kip Wells | | 348 | 309 | 39 |
| 2012-07-07 | @ SDN | 84 | W 6-5 | 44-40 | 2 | 34,222 | Homer Bailey | Clayton Richard | Homer Bailey | Clayton Richard | Aroldis Chapman | 354 | 314 | 40 |
| 2012-07-08 | @ SDN | 85 | W 4-2 | 45-40 | 2 | 24,032 | Johnny Cueto | Jason Marquis | Johnny Cueto | Jason Marquis | Aroldis Chapman | 358 | 316 | 42 |
| 2012-07-13 | vs SLN | 86 | W 5-3 | 46-40 | 2 | 40,217 | Mat Latos | Adam Wainwright | Alfredo Simon | Adam Wainwright | Aroldis Chapman | 363 | 319 | 44 |
| 2012-07-14 | vs SLN | 87 | W 3-2 | 47-40 | 2 | 37,583 | Mike Leake | Kyle Lohse | Sam LeCure | Victor Marte | | 366 | 321 | 45 |
| 2012-07-15 | vs SLN | 88 | W 4-2 | 48-40 | 1 | 39,280 | Homer Bailey | Jake Westbrook | Homer Bailey | Jake Westbrook | Aroldis Chapman | 370 | 323 | 47 |
| 2012-07-16 | vs ARI | 89 | L 3-5 | 48-41 | 1 | 27,735 | Bronson Arroyo | Wade Miley | Wade Miley | Bronson Arroyo | J.J. Putz | 373 | 328 | 45 |
| 2012-07-17 | vs ARI | 90 | W 4-0 | 49-41 | 1 | 19,142 | Johnny Cueto | Trevor Bauer | Johnny Cueto | Trevor Bauer | Aroldis Chapman | 377 | 328 | 49 |
| 2012-07-18 | vs ARI | 91 | L 1-7 | 49-42 | 2 | 26,077 | Mat Latos | Ian Kennedy | Ian Kennedy | Mat Latos | | 378 | 335 | 43 |
| 2012-07-19 | vs ARI | 92 | W 7-6 | 50-42 | 2 | 21,620 | Mike Leake | Joe Saunders | Alfredo Simon | Bryan Shaw | Aroldis Chapman | 385 | 341 | 44 |
| 2012-07-20 | vs MIL | 93 | W 3-1 | 51-42 | 2 | 30,247 | Homer Bailey | Marco Estrada | Homer Bailey | Marco Estrada | Aroldis Chapman | 388 | 342 | 46 |
| 2012-07-21 | vs MIL | 94 | W 6-2 | 52-42 | 2 | 40,090 | Bronson Arroyo | Yovani Gallardo | Bronson Arroyo | Yovani Gallardo | | 394 | 344 | 50 |
| 2012-07-22 | vs MIL | 95 | W 2-1 | 53-42 | 2 | 32,884 | Johnny Cueto | Michael Fiers | Johnny Cueto | Michael Fiers | Aroldis Chapman | 396 | 345 | 51 |
| 2012-07-23 | @ HOU | 96 | W 8-3 | 54-42 | 1 | 15,538 | Mat Latos | Wandy Rodriguez | Mat Latos | Wandy Rodriguez | | 404 | 348 | 56 |
| 2012-07-24 | @ HOU | 97 | W 4-2 | 55-42 | 1 | 15,908 | Mike Leake | Lucas Harrell | Mike Leake | Francisco Cordero | Aroldis Chapman | 408 | 350 | 58 |
| 2012-07-25 | @ HOU | 98 | W 5-3 | 56-42 | 1 | 16,077 | Homer Bailey | Bud Norris | Sean Marshall | Francisco Cordero | Aroldis Chapman | 413 | 353 | 60 |
| 2012-07-27 | @ COL | 99 | W 3-0 | 57-42 | 1 | 38,214 | Bronson Arroyo | Drew Pomeranz | Bronson Arroyo | Drew Pomeranz | Aroldis Chapman | 416 | 353 | 63 |
| 2012-07-28 | @ COL | 100 | W 9-7 | 58-42 | 1 | 42,826 | Johnny Cueto | Christian Friedrich | Johnny Cueto | Christian Friedrich | Aroldis Chapman | 425 | 360 | 65 |
| 2012-07-29 | @ COL | 101 | W 7-2 | 59-42 | 1 | 29,430 | Mat Latos | Jonathan Sanchez | Mat Latos | Jonathan Sanchez | | 432 | 362 | 70 |
| 2012-07-30 | vs SDN | 102 | W 5-11 | 60-42 | 1 | 28,140 | Mike Leake | Edinson Volquez | Edinson Volquez | Mike Leake | | 437 | 373 | 64 |
| 2012-07-31 | vs SDN | 103 | W 7-6 | 61-42 | 1 | 20,356 | Homer Bailey | Jason Marquis | Sean Marshall | Jason Marquis | Aroldis Chapman | 444 | 379 | 65 |
| 2012-08-01 | vs SDN | 104 | W 6-4 | 62-42 | 1 | 20,527 | Bronson Arroyo | Kip Wells | Bronson Arroyo | Kip Wells | Aroldis Chapman | 450 | 383 | 67 |
| 2012-08-02 | vs SDN | 105 | W 9-4 | 63-42 | 1 | 22,396 | Johnny Cueto | Ross Ohlendorf | Johnny Cueto | Ross Ohlendorf | | 459 | 387 | 72 |
| 2012-08-03 | vs PIT | 106 | W 3-0 | 64-42 | 1 | 40,829 | Mat Latos | Wandy Rodriguez | Mat Latos | Wandy Rodriguez | Aroldis Chapman | 462 | 387 | 75 |
| 2012-08-04 | vs PIT | 107 | W 5-4 | 65-42 | 1 | 41,577 | Mike Leake | James McDonald | Jonathan Broxton | Jared Hughes | Aroldis Chapman | 467 | 391 | 76 |
| 2012-08-05 | vs PIT | 108 | L 2-6 | 65-43 | 1 | 38,624 | Homer Bailey | A.J. Burnett | A.J. Burnett | Homer Bailey | Joel Hanrahan | 469 | 397 | 72 |
| 2012-08-06 | @ MIL | 109 | L 3-6 | 65-44 | 1 | 31,319 | Bronson Arroyo | Yovani Gallardo | Yovani Gallardo | Bronson Arroyo | John Axford | 472 | 403 | 69 |
| 2012-08-07 | @ MIL | 110 | L 1-3 | 65-45 | 1 | 41,213 | Johnny Cueto | Michael Fiers | Michael Fiers | Johnny Cueto | Jim Henderson | 473 | 406 | 67 |
| 2012-08-08 | @ MIL | 111 | L 2-3 | 65-46 | 1 | 33,788 | Mat Latos | Randy Wolf | John Axford | Jonathan Broxton | Jim Henderson | 475 | 409 | 66 |
| 2012-08-09 | @ CHN | 112 | L 3-5 | 65-47 | 1 | 33,397 | Mike Leake | Chris Volstad | Shawn Camp | Sean Marshall | Carlos Marmol | 478 | 414 | 64 |
| 2012-08-10 | @ CHN | 113 | L 10-8 | 65-48 | 1 | 36,891 | Homer Bailey | Justin Germano | Homer Bailey | Justin Germano | Aroldis Chapman | 488 | 422 | 66 |
| 2012-08-11 | @ CHN | 114 | W 4-2 | 66-48 | 1 | 40,602 | Bronson Arroyo | Travis Wood | Bronson Arroyo | James Russell | Aroldis Chapman | 492 | 424 | 68 |
| 2012-08-12 | @ CHN | 115 | W 3-0 | 67-48 | 1 | 35,461 | Johnny Cueto | Brooks Raley | Johnny Cueto | Brooks Raley | Aroldis Chapman | 495 | 424 | 71 |
| 2012-08-14 | vs NYN | 116 | W 3-0 | 68-48 | 1 | 26,113 | Mat Latos | Chris Young | Jose Arredondo | Manny Acosta | | 498 | 424 | 74 |
| 2012-08-15 | vs NYN | 117 | W 6-1 | 69-48 | 1 | 26,082 | Mike Leake | R.A. Dickey | Mike Leake | R.A. Dickey | | 504 | 425 | 79 |
| 2012-08-16 | vs NYN | 118 | L 4-8 | 69-49 | 1 | 23,137 | Homer Bailey | Matt Harvey | Matt Harvey | Homer Bailey | Jon Rauch | 508 | 433 | 75 |
| 2012-08-17 | vs CHN | 119 | W 7-3 | 70-49 | 1 | 35,332 | Bronson Arroyo | Travis Wood | Bronson Arroyo | Travis Wood | | 515 | 436 | 79 |
| 2012-08-18 | vs CHN | 120 | W 5-3 | 71-50 | 2 | 28,754 | Johnny Cueto | Jeff Samardzija | Johnny Cueto | Jeff Samardzija | Aroldis Chapman | 520 | 439 | 81 |
| 2012-08-18 | vs CHN | 121 | L 7-9 | 71-50 | 2 | 41,236 | Todd Redmond | Brooks Raley | Brooks Raley | Todd Redmond | Carlos Marmol | 527 | 448 | 79 |
| 2012-08-19 | vs CHN | 122 | W 5-4 | 72-50 | 1 | 41,615 | Mat Latos | Chris Volstad | Aroldis Chapman | Shawn Camp | | 532 | 452 | 80 |
| 2012-08-20 | @ PHI | 123 | W 5-12 | 73-50 | 1 | 44,341 | Mike Leake | Roy Halladay | Roy Halladay | Mike Leake | | 537 | 464 | 73 |
| 2012-08-21 | @ PHI | 124 | W 5-4 | 74-50 | 1 | 45,091 | Homer Bailey | Cliff Lee | Jonathan Broxton | Jonathan Papelbon | Aroldis Chapman | 542 | 468 | 74 |
| 2012-08-22 | @ PHI | 125 | W 3-2 | 75-50 | 1 | 41,794 | Bronson Arroyo | Vance Worley | Bronson Arroyo | Vance Worley | Aroldis Chapman | 545 | 470 | 75 |
| 2012-08-23 | @ PHI | 126 | L 3-4 | 75-51 | 1 | 41,972 | Johnny Cueto | Cole Hamels | Raul Valdes | Alfredo Simon | | 548 | 474 | 74 |
| 2012-08-24 | vs SLN | 127 | L 5-8 | 75-52 | 1 | 36,162 | Mat Latos | Lance Lynn | Joe Kelly | Mat Latos | Jason Motte | 553 | 482 | 71 |
| 2012-08-25 | vs SLN | 128 | W 8-2 | 76-52 | 1 | 41,680 | Mike Leake | Jaime Garcia | Mike Leake | Jaime Garcia | | 561 | 484 | 77 |
| 2012-08-26 | vs SLN | 129 | L 2-8 | 76-53 | 1 | 31,564 | Homer Bailey | Adam Wainwright | Adam Wainwright | Homer Bailey | | 563 | 492 | 71 |
| 2012-08-27 | @ ARI | 130 | W 3-2 | 77-53 | 1 | 17,966 | Bronson Arroyo | Tyler Skaggs | Bronson Arroyo | Tyler Skaggs | Aroldis Chapman | 566 | 494 | 72 |
| 2012-08-28 | @ ARI | 131 | W 5-2 | 78-53 | 1 | 20,550 | Johnny Cueto | Wade Miley | Johnny Cueto | Wade Miley | Aroldis Chapman | 571 | 496 | 75 |
| 2012-08-29 | @ ARI | 132 | W 6-2 | 79-53 | 1 | 18,451 | Mat Latos | Patrick Corbin | Mat Latos | Patrick Corbin | | 577 | 498 | 79 |
| 2012-08-31 | @ HOU | 133 | W 9-3 | 80-53 | 1 | 15,287 | Mike Leake | Fernando Abad | Mike Leake | Fernando Abad | | 586 | 501 | 85 |
| 2012-09-01 | @ HOU | 134 | L 1-2 | 80-54 | 1 | 18,316 | Homer Bailey | Lucas Harrell | Wilton Lopez | Sean Marshall | | 587 | 503 | 84 |
| 2012-09-02 | @ HOU | 135 | W 5-3 | 81-54 | 1 | 17,291 | Bronson Arroyo | Bud Norris | Jose Arredondo | Xavier Cedeno | Aroldis Chapman | 592 | 506 | 86 |
| 2012-09-03 | vs PHI | 136 | L 2-4 | 81-55 | 1 | 22,487 | Johnny Cueto | Tyler Cloyd | Tyler Cloyd | Johnny Cueto | Phillippe Aumont | 594 | 510 | 84 |
| 2012-09-04 | vs PHI | 137 | W 2-1 | 82-55 | 1 | 17,806 | Mat Latos | Kyle Kendrick | Mat Latos | Kyle Kendrick | Aroldis Chapman | 596 | 511 | 85 |
| 2012-09-05 | vs PHI | 138 | L 2-6 | 82-56 | 1 | 19,267 | Mike Leake | Roy Halladay | Roy Halladay | Mike Leake | | 598 | 517 | 81 |
| 2012-09-07 | vs HOU | 139 | L 3-5 | 82-57 | 1 | 23,785 | Homer Bailey | Lucas Harrell | Hector Ambriz | Aroldis Chapman | Wilton Lopez | 601 | 522 | 79 |
| 2012-09-08 | vs HOU | 140 | W 5-1 | 83-57 | 1 | 35,018 | Bronson Arroyo | Bud Norris | Bronson Arroyo | Bud Norris | | 606 | 523 | 83 |
| 2012-09-09 | vs HOU | 141 | L 1-5 | 83-58 | 1 | 33,438 | Johnny Cueto | Edgar Gonzalez | Edgar Gonzalez | Johnny Cueto | | 607 | 528 | 79 |
| 2012-09-10 | vs PIT | 142 | W 4-3 | 84-58 | 1 | 16,577 | Mat Latos | Wandy Rodriguez | Alfredo Simon | Rick van den Hurk | | 611 | 531 | 80 |
| 2012-09-11 | vs PIT | 143 | W 5-3 | 85-58 | 1 | 19,620 | Mike Leake | Kevin Correia | Mike Leake | Kevin Correia | Jonathan Broxton | 616 | 534 | 82 |
| 2012-09-12 | vs PIT | 144 | W 2-1 | 86-58 | 1 | 21,203 | Homer Bailey | A.J. Burnett | Homer Bailey | A.J. Burnett | J.J. Hoover | 618 | 535 | 83 |
| 2012-09-14 | @ MIA | 145 | L 0-4 | 86-59 | 1 | 27,111 | Bronson Arroyo | Jacob Turner | Jacob Turner | Bronson Arroyo | | 618 | 539 | 79 |
| 2012-09-15 | @ MIA | 146 | L 4-6 | 86-60 | 1 | 27,502 | Johnny Cueto | Mark Buehrle | Mark Buehrle | Johnny Cueto | Steve Cishek | 622 | 545 | 77 |
| 2012-09-16 | @ MIA | 147 | W 5-4 | 87-60 | 1 | 24,983 | Mat Latos | Ricky Nolasco | Logan Ondrusek | Carlos Zambrano | Jonathan Broxton | 627 | 549 | 78 |
| 2012-09-18 | @ CHN | 148 | W 3-1 | 88-60 | 1 | 32,547 | Homer Bailey | Justin Germano | Homer Bailey | Justin Germano | Jonathan Broxton | 630 | 550 | 80 |
| 2012-09-19 | @ CHN | 149 | W 6-5 | 89-60 | 1 | 31,001 | Mike Leake | Chris Rusin | Logan Ondrusek | Alberto Cabrera | Jonathan Broxton | 636 | 555 | 81 |
| 2012-09-20 | @ CHN | 150 | W 5-3 | 90-60 | 1 | 25,891 | Johnny Cueto | Jason Berken | Johnny Cueto | Manuel Corpas | Alfredo Simon | 641 | 558 | 83 |
| 2012-09-21 | vs LAN | 151 | L 1-3 | 90-61 | 1 | 35,397 | Bronson Arroyo | Joe Blanton | Ronald Belisario | Sam LeCure | Brandon League | 642 | 561 | 81 |
| 2012-09-22 | vs LAN | 152 | W 6-0 | 91-61 | 1 | 41,117 | Mat Latos | Stephen Fife | Mat Latos | Stephen Fife | | 648 | 561 | 87 |
| 2012-09-23 | vs LAN | 153 | L 3-5 | 91-62 | 1 | 32,932 | Homer Bailey | Clayton Kershaw | Shawn Tolleson | Homer Bailey | Brandon League | 651 | 566 | 85 |
| 2012-09-25 | vs MIL | 154 | W 4-2 | 92-62 | 1 | 18,155 | Johnny Cueto | Michael Fiers | Johnny Cueto | Michael Fiers | Aroldis Chapman | 655 | 568 | 87 |
| 2012-09-26 | vs MIL | 155 | L 1-8 | 92-63 | 1 | 20,570 | Bronson Arroyo | Shaun Marcum | Shaun Marcum | Bronson Arroyo | | 656 | 576 | 80 |
| 2012-09-27 | vs MIL | 156 | W 2-1 | 93-63 | 1 | 23,411 | Mat Latos | Wily Peralta | Jonathan Broxton | John Axford | | 658 | 577 | 81 |
| 2012-09-28 | @ PIT | 157 | W 1-0 | 94-63 | 1 | 34,796 | Homer Bailey | A.J. Burnett | Homer Bailey | A.J. Burnett | | 659 | 577 | 82 |
| 2012-09-29 | @ PIT | 158 | L 1-2 | 94-64 | 1 | 38,623 | Mike Leake | Kyle McPherson | Joel Hanrahan | Jonathan Broxton | | 660 | 579 | 81 |
| 2012-09-30 | @ PIT | 159 | W 4-3 | 95-64 | 1 | 32,814 | Johnny Cueto | Wandy Rodriguez | Sean Marshall | Joel Hanrahan | Aroldis Chapman | 664 | 582 | 82 |
| 2012-10-01 | @ SLN | 160 | L 2-4 | 95-65 | 1 | 38,480 | Bronson Arroyo | Jaime Garcia | Jaime Garcia | Bronson Arroyo | Jason Motte | 666 | 586 | 80 |
| 2012-10-02 | @ SLN | 161 | W 3-1 | 96-65 | 1 | 39,644 | Mat Latos | Chris Carpenter | Mat Latos | Chris Carpenter | Aroldis Chapman | 669 | 587 | 82 |
| 2012-10-03 | @ SLN | 162 | L 0-1 | 96-66 | 1 | 42,509 | Homer Bailey | Shelby Miller | Victor Marte | Jonathan Broxton | Jason Motte | 669 | 588 | 81 |