He attended Iron Mountain High School where he played fullback on the 1926 football team that won the title of Menominee Range champions.

[6] In 1954, he was hired by Michigan Technological University as a physical education instructor and assistant football coach with responsibilities for the linemen.

[6] In July 1957, after three years as an assistant to Al Bovard, LaJeunesse was promoted to the head football coach at Michigan Tech.

[8] La Jeunesse also served as the coach of the swim and softball teams and equipment manager during his tenure at Michigan Tech.

[12] Michigan Tech has established the Omer LaJeunesse Scholastic Achievement Award which is given annually to a football player with the highest grade point average.