The 36-year-old Soria has experience as a closer with 223 saves over his 13-year career, but he's served mostly as a bridge option in recent seasons.
Soria spent the last two seasons in Oakland's bullpen. He posted a 3.94 ERA and 1.08 WHIP over 91 1/3 innings.
The two-time All-Star is no stranger to the Rangers, either, as he appeared in 61 games for the team in 2013 and 2014.
The Astros have already been aggressive in improving their bullpen so far this winter by signing Baez and right-hander Ryne Stanek.