The power display began with a slam off rookie Jon Gray in the Mets' 6-run second inning. He led off the fourth with his second homer, this one off reliever Christian Bergman and his third, a two-run shot off Christian Friedrich, snapped an 8-8 tie in the sixth.
The seven RBIs represented a career-high for Cespedes, who was acquired from the Detroit Tigers in a trade deadline deal on July 31. They are also the third most RBIs in a game by a Mets player in team history. Carlos Delgado holds the team record with 9.
Cespedes has hit five home runs since joining the Mets and has 23 home runs overall.
It was the third time this season a Mets player has hit three home runs in a game. Lucas Duda was the last to accomplish the feat on July 29 against San Diego.