Mayne started at ESPN in 1994 as a "SportSmash" anchor on ESPN2, and soon moved over to the main network. He became well known for his dry sense of humor and his unique home run calls, such as "Yahtzee!", "I am amused by the simplicity of this game!" and "I am king of the diamond! Let there be an abundant clubhouse feast! Bring me the finest meats and cheeses in all the land!". He would also routinely thank the viewers for having electricity.

For a time, he served as co-anchor of the 11PM SportsCenter with Dan Patrick, and also hosted the game show 2 Minute Drill. Kenny is now most often seen as commentator for select horse racing events, as well as providing offbeat feature stories on Sunday NFL Countdown in a weekly segment called "The Mayne Event."

Kenny graduated from UNLV in 1982, where he was the back-up quarterback and ahead of future NFL star Randall Cunningham on the depth chart.