Thomas had been on the injured list since the preseason, when he suffered a rib injury. The Texans have been playing Darren Fells and Jordan Akins at tight ned this season.
The Texans also activated safety Jonathan Owens from the practice squad, a numbers move with safeties Justin Reid and Mike Adams out for Thursday night's game against the Colts due to concussions.
In other roster moves, the Texans waived defensive end Joel Heath and wide receiver Steven Mitchell Jr. from the active roster.