Thieneman was selected by Chicago in the first round (No. 25 overall) of the 2026 NFL Draft. An AP First-Team All-America selection in 2025, Thieneman started all 15 games at Oregon (2025), earning First-Team All-Big Ten Conference honors after totaling 86 tackles, two interceptions and seven total passes defensed. Thieneman transferred to Oregon after two seasons at Purdue (2023-24), starting his career with the Boilermakers with AP Third-Team All-America recognition and earning First-Team Freshman All-America status. Over his two seasons at Purdue, Thieneman started all 24 games played, totaling over 100 tackles in each of his two seasons of action, amassing six interceptions. As a freshman (2023), Thieneman was named the recipient of the Thompson-Randle El Big Ten Freshman of the Year Award.