| 1958-12-05 | Joey Amalfitano | Released by Giants. | 2B-3B | 5-11 | 180 | R | R | 1934-01-23 | San Pedro,CA |
| MLB | 1954-1967 | 1954-1967 |
| 1958-12-03 | Valmy Thomas | Traded by Giants with Ruben Gomez to Phillies for Jack Sanford. | C-3B | 5-9 | 165 | R | R | 1928-10-21 | Santurce,PR |
| MLB | 1957-1961 | 1957-1961 |
| 1958-12-03 | Ruben Gomez | Traded by Giants with Valmy Thomas to Phillies for Jack Sanford. | P-OF | 6-0 | 175 | R | R | 1927-07-13 | Arroyo,PR |
| MLB | 1953-1967 | 1953-1967 |
| 1958-12-03 | Jack Sanford | Traded by Phillies to Giants for Ruben Gomez and Valmy Thomas. | P | 6-0 | 190 | R | R | 1929-05-18 | Wellesley Hills,MA |
| MLB | 1956-1967 | 1956-1967 |
| 1958-12-02 | Chuck Hiller | Selected by Giants from Indians in the minor league draft. | 2B-3B | 5-11 | 170 | L | R | 1934-10-01 | Johnsburg,IL | 1957- 0- 0-CLE
| MLB | 1961-1968 | 1961-1968 |
| 1958-10-08 | Benny Valenzuela | Traded by Cardinals with Hobie Landrith and Billy Muffett to Giants for Ernie Broglio and Marv Grissom. | 3B | 5-10 | 175 | R | R | 1933-06-02 | Los Mochis,MX |
| MLB | 1958-1958 | 1958-1958 |
| 1958-10-08 | Billy Muffett | Traded by Cardinals with Benny Valenzuela and Hobie Landrith to Giants for Ernie Broglio and Marv Grissom. | P | 6-1 | 198 | R | R | 1930-09-21 | Hammond,IN |
| MLB | 1957-1962 | 1957-1962 |
| 1958-10-08 | Hobie Landrith | Traded by Cardinals with Benny Valenzuela and Billy Muffett to Giants for Ernie Broglio and Marv Grissom. | C | 5-10 | 170 | L | R | 1930-03-16 | Decatur,IL |
| MLB | 1950-1963 | 1950-1963 |
| 1958-10-08 | Marv Grissom | Traded by Giants with Ernie Broglio to Cardinals for Benny Valenzuela, Hobie Landrith and Billy Muffett. | P | 6-3 | 195 | R | R | 1918-03-31 | Los Molinos,CA |
| MLB | 1946-1959 | 1946-1959 |
| 1958-10-08 | Ernie Broglio | Traded by Giants with Marv Grissom to Cardinals for Benny Valenzuela, Hobie Landrith and Billy Muffett. | P | 6-2 | 200 | R | R | 1935-08-27 | Berkeley,CA | 1954- 0- 0-CIN
| MLB | 1959-1966 | 1959-1966 |
| 1958-10-05 | Pete Burnside | Purchased by Tigers from Giants. | P | 6-2 | 190 | R | L | 1930-07-02 | Evanston,IL |
| MLB | 1955-1963 | 1955-1963 |
| 1958-08-25 | Jesus Alou | Signed as undrafted amateur Free Agent by Giants. | OF-DH | 6-2 | 195 | R | R | 1942-03-24 | Haina,DR | 1958- 0- 0-SFN
| MLB | 1963-1979 | 1959-1979 |
| 1958-07-15 | Don Johnson | Purchased by Giants from Toronto (International). | P | 6-3 | 200 | R | R | 1926-11-12 | Portland,OR |
| MLB | 1947-1958 | 1947-1958 |
| 1958-06-07 | Jim Constable | Claimed on waivers by Indians from Giants. | P | 6-1 | 185 | B | L | 1933-06-14 | Jonesborough,TN |
| MLB | 1956-1963 | 1956-1963 |
| 1958-06-03 | Gaylord Perry | Signed as undrafted amateur Free Agent by Giants. | P | 6-4 | 215 | R | R | 1938-09-15 | Williamston,NC | 1958- 0- 0-SFN
| MLB | 1962-1983 | 1958-1983 |
| 1958-05-17 | Nick Testa | Released by Giants. | C | 5-8 | 180 | R | R | 1928-06-19 | New York,NY |
| --- | | |
| 1958-04-03 | Bob Speake | Traded by Cubs with Cash to Giants for Bobby Thomson. | OF-1B | 6-1 | 178 | L | L | 1930-08-22 | Springfield,MO |
| MLB | 1955-1959 | 1955-1959 |
| 1958-04-03 | Bobby Thomson | Traded by Giants to Cubs for Bob Speake and Cash. | OF-3B | 6-2 | 185 | R | R | 1923-10-25 | Glasgow,ST |
| MLB | 1946-1960 | 1946-1960 |
| 1958-04-02 | Ray Katt | Traded by Giants to Cardinals for Jim King. | C | 6-2 | 200 | R | R | 1927-05-09 | New Braunfels,TX |
| MLB | 1952-1959 | 1952-1959 |
| 1958-04-02 | Jim King | Traded by Cardinals to Giants for Ray Katt. | OF-C | 6-0 | 185 | L | R | 1932-08-27 | Elkins,AR |
| MLB | 1955-1967 | 1955-1967 |
| 1958-03-24 | Foster Castleman | Purchased by Orioles from Giants. | 3B-SS | 6-0 | 175 | R | R | 1931-01-01 | Nashville,TN |
| MLB | 1954-1958 | 1954-1958 |
| 1958-03-21 | Don Mueller | Purchased by White Sox from Giants. | OF | 6-0 | 185 | L | R | 1927-04-14 | St. Louis,MO |
| MLB | 1948-1959 | 1948-1959 |
| 1958-01-28 | Jim Finigan | Traded by Tigers with Cash to Giants for Gail Harris and Ozzie Virgil. | 3B-2B | 5-11 | 175 | R | R | 1928-08-19 | Quincy,IL |
| MLB | 1954-1959 | 1954-1959 |
| 1958-01-28 | Ozzie Virgil | Traded by Giants with Gail Harris to Tigers for Jim Finigan and Cash. | 3B-C | 6-1 | 195 | R | R | 1933-05-17 | Monte Cristi,DR |
| MLB | 1956-1969 | 1956-1969 |
| 1958-01-28 | Gail Harris | Traded by Giants with Ozzie Virgil to Tigers for Jim Finigan and Cash. | 1B | 6-0 | 195 | L | L | 1931-10-15 | Abingdon,VA |
| MLB | 1955-1960 | 1955-1960 |
| 1958-01-01 | Tom Haller | Signed as undrafted amateur Free Agent by Giants. | C-OF | 6-4 | 195 | L | R | 1937-06-23 | Lockport,IL | 1958- 0- 0-SFN
| MLB | 1961-1972 | 1958-1972 |
| 1958-01-01 | Dick LeMay | Signed as undrafted amateur Free Agent by Giants. | P | 6-3 | 190 | L | L | 1938-08-28 | Cincinnati,OH | 1958- 0- 0-SFN
| MLB | 1961-1963 | 1961-1963 |
| 1958-01-01 | Ron Herbel | Signed as undrafted amateur Free Agent by Giants. | P | 6-1 | 195 | R | R | 1938-01-16 | Denver,CO | 1958- 0- 0-SFN
| MLB | 1963-1971 | 1963-1971 |
| 1958-01-01 | Eddie Fisher | Signed as undrafted amateur Free Agent by Giants. | P | 6-2 | 200 | R | R | 1936-07-16 | Shreveport,LA | 1958- 0- 0-SFN
| MLB | 1959-1973 | 1958-1973 |
| 1958-01-01 | Charlie Dees | Signed as undrafted amateur Free Agent by Giants. | 1B | 6-1 | 173 | L | L | 1935-06-24 | Birmingham,AL | 1958- 0- 0-SFN
| MLB | 1963-1965 | 1963-1965 |
| 1958-01-01 | Jose Vidal | Signed as undrafted amateur Free Agent by Giants. | OF-1B | 6-0 | 190 | R | R | 1940-04-03 | Batey Lechugas,DR | 1968- 0- 0-SFN
| MLB | 1966-1969 | 1966-1969 |
| 1958-01-01 | Jose Tartabull | Signed as undrafted amateur Free Agent by Giants. | OF | 5-11 | 165 | L | L | 1938-11-27 | Cienfuegos,CU | 1958- 0- 0-SFN
| MLB | 1962-1970 | 1962-1970 |
| 1958-01-01 | Freddie Velazquez | Signed as undrafted amateur Free Agent by Giants. | C | 6-1 | 185 | R | R | 1937-12-06 | Santo Domingo,DR | 1958- 0- 0-SFN
| MLB | 1969-1973 | 1969-1973 |