Texans announce signings, cuts
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.