Clowney flew to Philadelphia on Thursday to undergo an examination for a groin issue, then underwent the surgery. O'Brien said Clowney will be ready for training camp.
O'Brien said it hadn't bothered Clowney for long.
"We just looked at it as, let's take care of it now, and he'll be ready for training camp," O'Brien said. "And we're looking forward to seeing him in training camp."
The Texans drafted Clowney first overall out of South Carolina last month. He's been a full participant in the team's voluntary offseason program, previously missing only practices that NFL rules didn't allow him to attend when he was invited to the NFLPA's rookie premiere.
The outside linebacker reportedly had a nagging groin injury during a very impressive showing at his pro day in April.