Gallegos was recalled from Triple-A Scranton/Wilkes-Barre on Wednesday.
Gallegos will join the Yankees bullpen in place of Bryan Mitchell, who was optioned to Triple-A after yielding two unearned runs on two hits and a walk Tuesday against the Orioles. The 25-year-old Gallegos made four appearances with the Yankees earlier this season, giving up three earned runs and turning in a 1.88 WHIP over 5.1 innings.