| | | Thursday, July 2nd, 2020 | | Signed 3B Chris Winter to a 4-year contract extension worth a total of $52,440,000. |
| Monday, May 25th, 2020 | | Placed 1B Sal Harris on the active roster. | | Activated 1B Sal Harris from the disabled list. |
| Thursday, April 30th, 2020 | | Failed to sign 3rd round draft pick Andrés Guzmán. |
| Monday, March 23rd, 2020 | | Signed Juan Luque to a minor league contract with a signing bonus of $290,000. |
| Sunday, March 15th, 2020 | | Signed Matt Westbrook to a minor league contract with a signing bonus of $125,000. |
| Friday, March 13th, 2020 | | Signed Patrick Youmans to a minor league contract with a signing bonus of $425,000. |
| Wednesday, March 11th, 2020 | | Signed Kenny Thompson to a minor league contract with a signing bonus of $750,000. |
| Sunday, March 8th, 2020 | | Signed Brad Williamson to a minor league contract with a signing bonus of $125,000. |
| Sunday, March 1st, 2020 | | Drafted CL Kenny Thompson in the 2020 first-year player draft (Round 1, Pick 27, 27th overall pick). | | Drafted MR Patrick Youmans in the 2020 first-year player draft (Round 2, Pick 27, 54th overall pick). | | Drafted MR Juan Luque in the 2020 first-year player draft (Round 3, Pick 16, 70th overall pick). | | Drafted SP Andrés Guzmán in the 2020 first-year player draft (Round 3, Pick 28, 82nd overall pick). | | Drafted SP Matt Westbrook in the 2020 first-year player draft (Round 4, Pick 30, 111st overall pick). | | Drafted 1B Brad Williamson in the 2020 first-year player draft (Round 5, Pick 27, 137th overall pick). | | Drafted C Mark Snijders in the 2020 first-year player draft (Round 6, Pick 24, 164th overall pick). | | Drafted SP Ángel Torres in the 2020 first-year player draft (Round 7, Pick 24, 191st overall pick). | | Drafted LF César Guzmán in the 2020 first-year player draft (Round 8, Pick 24, 215th overall pick). | | Drafted MR Rick Turner in the 2020 first-year player draft (Round 9, Pick 24, 239th overall pick). | | Drafted C Ty Jackson in the 2020 first-year player draft (Round 10, Pick 24, 263rd overall pick). |
| Monday, February 24th, 2020 | | Traded 30-year-old starting pitcher Franklin Grissom to the San Diego Surf, getting a 3rd round draft pick and a 3rd round draft pick in return. |
| Saturday, December 7th, 2019 | | Signed MR José Gonzáles to a 3-year contract extension worth a total of $12,420,000. |
| Thursday, November 28th, 2019 | | Signed CF Quentin Fuller to a 6-year contract extension worth a total of $87,000,000. |
| Sunday, November 24th, 2019 | | Signed LF Pancho Martínez to a 4-year contract extension worth a total of $42,600,000. | | Signed SP Edwin White to a 7-year contract extension worth a total of $77,000,000. |
| Tuesday, November 19th, 2019 | | 2B Juan Olvera received a 1-year contract through automatic renewal worth a total of $400,000. | | LF Preston Feather received a 1-year contract through automatic renewal worth a total of $400,000. | | 1B Sal Harris received a 1-year contract through automatic renewal worth a total of $400,000. |
| Saturday, November 16th, 2019 | | C Héctor Cruz received a 1-year contract through arbitration worth a total of $600,000. | | CF Quentin Fuller received a 1-year contract through arbitration worth a total of $8,500,000. | | MR Jesús Rúbio received a 1-year contract through arbitration worth a total of $1,300,000. | | MR Yin-reng Xiong received a 1-year contract through arbitration worth a total of $975,000. | | RF Jesús Vásquez received a 1-year contract through arbitration worth a total of $600,000. |
| Thursday, October 31st, 2019 | | Signed MR Pablo Pantoja to a minor league contract extension. | | Signed 1B Donnie Alexander to a minor league contract extension. | | Signed SP Jason Knight to a minor league contract extension. |
| Wednesday, October 30th, 2019 | | Signed MR Juan Díaz to a minor league contract extension. |
| Sunday, October 27th, 2019 | | Signed MR Zheng-ze Pai to a minor league contract extension. |
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