The 29-year-old Perez was designated for assignment on Friday. A lefty hitter, he batted .150 with six home runs and 11 RBIs in 39 games and 107 at-bats this season.
In parts of five seasons with the Pirates and Tampa Bay, he is hitting .175 with 15 home runs and 58 RBIs.
On Friday, the Mets got designated hitter Daniel Vogelbach from the Pirates for rookie reliever Colin Holderman.
Mets infielder Travis Blankenhorn was designated for assignment to make room for Perez. Blankenhorn was selected from Triple-A Syracuse and started at DH on Friday night in a 4-1 loss to San Diego.