Clowney will begin training camp on the list and still count against the Texans' active roster. The move allows them to keep Clowney on the PUP list into the regular season if necessary, but he can come off at any time during training camp.
The Texans selected Clowney first overall in 2014, but he was able to play in only four games last season due to an injury.
Clowney suffered a lateral meniscus tear in the Texans' first game of the season against Washington.
He had arthroscopic knee surgery to repair the injury the next day and worked to return to the field during the season. Swelling and pain in his knee prevented his full efficacy, and Clowney ultimately underwent a second, more serious surgery.
Clowney had microfracture surgery on that right knee in December, a procedure in which tiny fractures are made in the bones around the knee to improve blood flow to the meniscus, the cartilage that pads the knee joint.
Clowney has undergone blood flow restriction therapy to help maintain his muscle strength while undergoing rehab.
"I think all of us can't wait to see him back out there and see what he can do," Texans defensive end J.J. Watt said. "He obviously has a lot of great potential, and we hope he realizes that potential. However we can help him, we're going to try and help him realize it."