Stillwagon was a three-year starter with the Ohio StateBuckeyes. He was a consensus All-American selection as a junior and senior, and won the Outland Trophy and was the first-ever winner of the Lombardi Award. He also won the 1970 UPI Lineman of the Year. Stillwagon was one of the so-called Super Sophomores of 1968, guiding the Buckeyes to an undefeated season and a consensus national championship. Stillwagon and the other Super Sophomores finished their college careers with a record of 27–2.