He performed many character voices for Disney. His distinctive voice can be heard in movies such as Lady and the Tramp, Sleeping Beauty, Donald Duck and His Friends, One Hundred and One Dalmatians, Mary Poppins and Bedknobs and Broomsticks.
He also did voices for several Disney Attractions, such as the famous Big Thunder Mountain Railroad safety spiel, the laughing hyenas in "it's a small world" (recycled from Lady and the Tramp, and later heard in the 1979 horror film Tourist Trap, and as the original voice of Ripper Roo in the Crash Bandicoot video game series), Ben Franklin in Epcot's The American Adventure, and Zeke in Country Bear Jamboree.
- McKennon's hyena laugh from Lady and the Tramp was then used for the laugh of Ripper Roo in the Crash Bandicoot video game franchise, and the hyenas in the "it's a small world" attraction. The laugh was also used in various films such as the 1979 horror film Tourist Trap and the 2003 Christmas comedy film Elf.