Perez will serve as the Mets' opening pitcher for Sunday's contest against Philadelphia, Max Goodman of NJ.com reports.
Perez began the campaign with Washington before joining the Mets on a minor-league deal in early May. The lefty hurler was brought up to the big-league club May 30 and has appeared in 10 contests, posting a 3.68 ERA, 1.02 WHIP and 14:1 K:BB over 14.2 innings. Perez hasn't tossed more than 32 pitches in an outing this season, so the Mets are unlikely to have him cover more than an inning or two before he turns the game over to the bullpen. Both Tobias Myers and Kodai Senga are available on four days' rest and could be candidates to cover multiple innings in relief.