He is best known as a key reserve on the University of Kentucky's 1958 NCAA championship team.

Mills was recruited to play basketball at the University of Kentucky by head coach Adolph Rupp following an All-American season at Berea Community High School.

He played a significant role in the 1958 Championship Game against Seattle after starting center Ed Beck was sidelined due to foul trouble.

Mills scored nine points off the bench, including a hook shot over Seattle's Elgin Baylor with 5:50 minutes left in the second half to give Kentucky the lead.

As a senior, he averaged 12.8 points and 12.9 rebounds per game and was named second team All-Southeastern Conference (SEC) by the Associated Press and first team All-SEC by the conference's coaches.