| 5/1/18 |
RHP Tyler Kinley returned to Miami Marlins from Minnesota Twins. |
| 5/2/18 |
Miami Marlins optioned SS JT Riddle to New Orleans Baby Cakes. |
| 5/2/18 |
Miami Marlins sent 1B Tomas Telis outright to New Orleans Baby Cakes. |
| 5/3/18 |
Miami Marlins activated RHP Tyler Cloyd from the paternity list. |
| 5/3/18 |
Miami Marlins optioned LHP Dillon Peters to New Orleans Baby Cakes. |
| 5/4/18 |
Miami Marlins signed free agent RHP Sergio Palacio to a minor league contract. |
| 5/10/18 |
Miami Marlins activated RHP Elieser Hernandez from the 10-day disabled list. |
| 5/10/18 |
Miami Marlins optioned RHP Merandy Gonzalez to Jacksonville Jumbo Shrimp. |
| 5/10/18 |
Miami Marlins signed free agent CF Anfernee Seymour to a minor league contract. |
| 5/16/18 |
Miami Marlins sent RHP Odrisamer Despaigne on a rehab assignment to Jupiter Hammerheads. |
| 5/17/18 |
Miami Marlins sent RHP Brett Graves on a rehab assignment to Jupiter Hammerheads. |
| 5/18/18 |
Miami Marlins designated RHP Junichi Tazawa for assignment. |
| 5/18/18 |
Miami Marlins optioned RHP Tyler Cloyd to New Orleans Baby Cakes. |
| 5/18/18 |
Miami Marlins recalled LHP Adam Conley from New Orleans Baby Cakes. |
| 5/18/18 |
Miami Marlins recalled LHP Dillon Peters from New Orleans Baby Cakes. |
| 5/21/18 |
Miami Marlins activated RHP Odrisamer Despaigne from the 7-day disabled list. |
| 5/21/18 |
Miami Marlins optioned LHP Dillon Peters to New Orleans Baby Cakes. |
| 5/21/18 |
Miami Marlins released RHP Junichi Tazawa. |
