Within two years, McMahon was Philadelphia's "Mr. Television," serving as host of 13 programs, including a cooking show, a quiz show, the "Million Dollar Movie" and a pioneer breakfast-hour show called "Strictly for the Girls."
In 1958, McMahon met the man who would forever alter his career and fortunes: Johnny Carson, a rising young comedian, who hired him to be his announcer on "Who Do You Trust?," a half-hour afternoon comedy quiz show on ABC.
McMahon's job consisted of introducing the contestants, doing the commercials and occasionally talking briefly to Carson at the beginning of the show. From the start, Carson made McMahon his comedy foil, and in so doing established an on-air relationship that would continue for nearly 34 years.
McMahon quickly became "Big Ed," the good-time guy who ate and drank too much.
"Ed is the announcer on the show," Carson once told his viewers, "only because he never passed the bar. In fact, Ed has never passed any bar."
When Carson moved to NBC to be host of "The Tonight Show" in October 1962, he took McMahon with him.
McMahon did the audience warmups and commercials, and he performed in sketches. But his primary job, McMahon wrote in his 1998 autobiography, "For Laughing Out Loud," was to be Carson's straight man.
"I had to support him, I had to help him get to the punch line, but while doing it I had to make it look as if I wasn't doing anything at all. The better I did it, the less it appeared as if I was doing it," he wrote.
McMahon said, however, that his role on the show was never strictly defined: "I was there when he needed me, and when he didn't, I moved down the couch and kept quiet."
One night, however, he didn't keep quiet when he should have.
During the show, Carson was explaining to McMahon that scientists had just completed a multimillion-dollar study about mosquitoes and had discovered that for some reason, mosquitoes were particularly attracted to extremely "warm-blooded, passionate people."
Hearing that, McMahon instinctively slapped his wrist and said, "Whoops, there's another one."
As the audience roared, Carson glared icily at McMahon.
"Well, then," Carson said, picking up a comically oversized can of insect spray, "I guess I won't be needing this $500 prop then, will I?"
The audience laughed again, but McMahon knew he had ruined the bit by stepping outside his role as straight man and stealing Carson's laugh. It was, McMahon later wrote, the only time Carson was angry with him.
Carson was so upset, biographer Laurence Leamer wrote in "King of the Night: The Life of Johnny Carson," that he told his manager the next day to get rid of McMahon.
"Johnny was very angry," Mary Stark, the wife of "Tonight Show" producer Art Stark, told Leamer. "Art went to bat for Ed and said it would be absolute suicide to fire him. There would be no way to keep it quiet."
Despite the on-air misstep, Carson paid tribute to his sidekick on the duo's last "Tonight Show" broadcast on May 22, 1992.
"Ed has been a rock for 30 years, sitting over here next to me. . . . We have been friends for 34 years. A lot of people who work together on television don't necessarily like each other. This hasn't been true. . . . We're good friends; you can't fake that on television."
During his years on "The Tonight Show," McMahon did a nightclub act that he took to Las Vegas and appeared in plays and in several films, including the original "Fun With Dick and Jane," starring George Segal and Jane Fonda.
He also served as co-host of the United Negro College Fund's telethon with singer Lou Rawls for many years and as co-host of Jerry Lewis' annual Muscular Dystrophy Assn. telethon for more than three decades.
Down-to-earth and approachable, McMahon was known to respond freely to fans' questions -- as well as to the inevitable requests from fans such as the tourist in Florida who took his picture and then pleaded with him, "Say it for me."
"What's your name?" McMahon inquired.
After being told, he boomed, "Heeeeere's Debbie!"
McMahon's first two marriages ended in divorce.
In addition to his wife, McMahon's survivors include his children Jeffrey, Lex, Claudia, Katherine and Linda.
Memorial services are pending.