| Date | Player | Position | Transaction |
|---|---|---|---|
| May 20 | David Aardsma | RP | Signed to a Minor League Contract by NY Mets |
| May 14 | Collin McHugh | SP/RP | Called Up from Minors by NY Mets |
| May 14 | Matt Fox | SP | Signed to a Minor League Contract by NY Mets |
| May 14 | Frank Francisco | RP | Recalled From Minors Rehab by NY Mets |
| May 13 | Andrew Brown | RF/LF | Sent to Minors by NY Mets |
| May 13 | Rick Ankiel | RF/CF | Signed as Free Agent by NY Mets (one-year contract) |
| May 13 | Jenrry Mejía | SP/RP | Transferred to 60-Day DL by NY Mets (Right elbow inflammation) |
| May 12 | Greg Burke | RP | Called Up from Minors by NY Mets |
| May 11 | Jenrry Mejía | SP/RP | Sent to Minors for Rehabilitation by NY Mets |
| May 5 | Frank Francisco | RP | Sent to Minors for Rehabilitation by NY Mets |
| May 3 | Collin Cowgill | CF/LF | Sent to Minors by NY Mets |
| May 3 | Andrew Brown | RF/LF | Purchased From Minors by NY Mets |