Jennings redshirted his true freshman season as he moved from defensive end to the outside linebacker position. He played as a key reserve as a redshirt freshman, finishing the year with 19 tackles (two for loss) and three quarterback hurries. Jennings became a starter during redshirt sophomore season and made 41 tackles, six for a loss, with one sack. Jennings suffered what was initially diagnosed to be a PCL injury in the final minutes of the 2018 Sugar Bowl against Clemson, causing him to miss the 2018 College Football Playoff National Championship Game. The injury was re-evaluated and Jennings was found to have also damaged an artery and developed a blood clot in his leg.