The 6-foot-1, 241-pound Williams was taken with the 124th overall pick out of Connecticut. He's one of five drafted players signed by Houston, also including tackle David Quessenberry, receiver Alan Bonner, defensive tackle Chris Jones and tight end Ryan Griffin.
Williams started 30 of 50 games he played in for Connecticut and had a school-record 30 1/2 career sacks.
Other signings, cuts this week
The Houston Texans announced they have signed free agent center Tyler Horn and released running back George Winn and tackle Dann O'Neill.
The team also said Wednesday it had signed running back/kick returner Deji Karim, announced earlier this week by his agent on Twitter.
Like Karim, Horn tried out at the Texans rookie mini-camp. Horn, signed out of Miami as a free agent by Atlanta in 2012, spent the final nine weeks of last season on the Tennessee Titans practice squad.
Both Winn and O'Neill signed with the Texans on May 10 as undrafted college free agents.