[1] He also helped guide the evolution of the rules of modern football, serving ten years on the college football rules committee (1922–1931), initially under Secretary Walter Camp and alongside Amos Alonzo Stagg.

Over the years, Ahearn served Kansas State in a variety of roles that included coach, professor, head of the Department of Physical Education, and director of athletics.

In 1905, he officially became the tenth head football coach at Kansas State, but was the first to hold the position for more than one year.

His 39 wins were the most in the history of Kansas State Wildcats football until Bill Snyder passed him in 1995.

From 1920 until 1947, Ahearn was the athletic director at Kansas State, during which time the school built Memorial Stadium, the Wildcats home football venue from 1922 until 1967.