The Rangers acquired Pennington from the Royals on Monday in exchange for right-hander Michael Lorenzen.
Pennington, 26, has made one scoreless appearance in the majors this season and boasts a 2.26 ERA and 79:20 K:BB across 59.2 innings at the Triple-A level in 2024. The left-hander will be assigned to Triple-A Round Rock for now but could contribute to the Rangers bullpen in the second half.