The Redskins also signed wide receiver Robert Davis from the practice squad, according to the team. Washington placed starting running back Derrius Guice and defensive lineman Caleb Brantley on injured reserve in corresponding roster moves.
Washington signed Colvin one day after he was officially released by the Texans. He was cut after struggling during Houston's Monday night loss to the New Orleans Saints.
Colvin allowed two touchdown passes, and gave up a key completion to Saints wide receiver Ted Ginn Jr. on New Orleans' game-winning drive.
The Texans originally signed Colvin to a four-year, $34 million contract last season. He is owed $7.5 million in guaranteed money.
Colvin joins a Redskins defensive backfield that consists of Josh Norman, Quinton Dunbar and Fabian Moreau at cornerback. For the Redskins' Week 2 matchup against the Dallas Cowboys, Dunbar is questionable with a knee injury, while Moreau is doubtful due to an ankle ailment.
Colvin has recorded five total tackles in one game this season.