The defensive end, ranked No. 11 overall among draft prospects by ESPN's Mel Kiper, said he made the choice before Clemson's regular-season finale against South Carolina and wanted to make it known so people would stop asking him.
Lawson leads the top-ranked Tigers with 10 sacks and 22.5 tackles for loss.
The Tigers (13-0) returned to practice Monday to prepare for No. 4 Oklahoma, whom they'll face in the College Football Playoff semifinals in the Orange Bowl on New Year's Eve.
Information from The Associated Press was used in this report.