The former Tonight Show sidekick passed away early Tuesday morning at the Ronald Reagan UCLA Medical Center in Los Angeles after battling poor health for some time.
He was diagnosed with systemic bone cancer and spent time in the hospital in February suffering from pneumonia.
And stars from the world of music and television turned out to pay tribute to him at the emotional service.
Natalie Cole, accompanied by Canadian musician David Foster, gave a touching performance of her song “Smile” at the ceremony.
McMahon's wife Pam and his children and grandchildren spoke of their love of the star to the gathered mourners.
TV host Jimmy Kimmel and Johnny Carson's former wife Joanna Carson were among the 200 guests who attended at the Forest Lawn Memorial Parks and Mortuaries in Los Angeles, according to Entertainment Tonight.
(c) 2009 WORLD ENTERTAINMENT NEWS NETWORK LTD. All global rights reserved. No unauthorized copying or re-distributing permitted.