Terms of the deal weren't disclosed.
Williams spent three seasons with the Titans and caught 84 passes for 1,139 yards and six touchdowns. He had 55 receptions for 719 yards and four touchdowns -- all career highs -- in 2007, but ankle injuries led the Titans to cut Williams at the end of training camp last year.
Williams was on hand for the start of Washington's voluntary spring practices on Monday.
The Redskins also signed wide receiver Trent Shelton, who spent 11 weeks on the Seattle Seahawks' practice squad last year. The team released tight end Devin Frischknecht, wide receiver John Halman, defensive tackle Brigham Harwell, linebacker Ronnie Palmer and offensive lineman Isaiah Ross.
Copyright 2009 by The Associated Press