Romero was recalled by the Phillies on Friday, Jim Salisbury of NBC Sports Philadelphia reports.
The 23-year-old was optioned to the alternate training site after serving as the 29th man for Thursday's doubleheader, but he'll quickly rejoin the team with Jose Alvarez (groin) placed on the injured list. Romero has yet to make his major-league debut and had a 6.88 ERA, 1.94 WHIP and 40:35 K:BB over 53.2 innings at Triple-A in 2019.