He graduated from the University of Nevada, Las Vegas in 1982 with a degree in broadcasting.While at UNLV, Mayne was a backup quarterback for two years and he later tried out for the Seattle Seahawks, but was not offered a contract.

Mayne then spent seven years (1982–89) at KSTW-TV in Seattle, Washington, working as a weekend sports anchor and weekday news reporter.

[citation needed] On January 17, 2007, ESPN signed Mayne to a one-year contract to do features and cover horse racing, as well as return to SportsCenter for about 50 shows in 2007.

In the first season the show visited six countries (England, Ireland, Brazil, South Africa, Thailand, and New Zealand) with Mayne participating in events like the King's Cup Elephant Polo tournament in Thailand, the world's longest par-3 hole (Extreme 19) in South Africa, and a road bowling match in Ireland.

A television version of Kenny Mayne's Wider World of Sports, featuring highlights from the internet series, aired on ESPN/ABC in December 2011.

Season 2 of Wider World of Sports featured visits to the Netherlands for canal jumping, Nicaragua for volcano boarding, Italy for the Palio di Siena horse race, Bosnia and Herzegovina for bridge diving at Stari Most, Switzerland for hornussen, and Scotland for the Highland Games.

A new contract with ESPN signed earlier that month set Mayne to anchor 70 episodes of SportsCenter and host 10 special features per year through 2015.

[16] From July–September 2021, Mayne along with another former ESPN anchor, Cari Champion, hosted streaming coverage of the 2020 Summer Olympics on Peacock called Tokyo Tonight.