Fehoko was a two-year starter for the Red Raiders and the No. 51 recruit in the ESPN 300 in 2015. He took five official visits this spring and chose LSU over Auburn, Georgia, Ole Miss and Louisville.
He'll have to sit out the 2017 season as a transfer, but Fehoko will have two seasons of eligibility with the Tigers.
Fehoko said the opportunity to play in the SEC and play for head coach Ed Orgeron, whose specialty is defensive linemen, made LSU an ideal fit.
"I think the X factor in this situation was Coach O," Fehoko told ESPN.com. "Having a head coach who's a D-line coach by trade, that was a no-brainer."
Fehoko also liked the opportunity he'll have at LSU in 2018 after four senior defensive linemen graduate. He called Orgeron on Monday morning to deliver the news.
"He had a big Cajun roar and he let out a big scream and passed the phone along to the whole staff," Fehoko said. "They were all excited. I had a FaceTime video chat with them and that place was turned upside-down by the time I hung up."