Maybin's third homer gave Florida a 7-3 lead with two outs in the bottom of the fifth.
Jorge Cantu had three hits and one RBI.
A run scored on a second-inning wild pitch by losing pitcher John Maine (6-6), and Brett Hayes hit a pinch-hit RBI double for the Marlins, who have won three of four to maintain their slim National League wild-card hopes.
The winner was starter Sean West (8-6).
Brendan Donnelly earned his first save.
New York's Fernando Tatis had two hits, including a two-run fourth-inning homer.
Luis Castillo had two hits and one RBI.
Carlos Beltran hit a solo homer.
David Wright had one RBI, while a run scored on Matt Lindstrom's throwing error for the Mets, who have lost four of five.