Harmon, who suffered from heart disease, died at his home in Los Angeles, said his wife, Susan.
"Bozo and Larry were one and the same," she told The Times on Thursday. "He's lived it and breathed it since he bought [the rights] from Capitol Records in the '50s. He made it what it is, and it's been his life."
Bozo was created for a series of Capitol children's records in 1946, with Vance "Pinto" Colvig, the voice of Walt Disney's Goofy, providing the clown's voice.
Several years later, according to a 1996 Associated Press story, Harmon answered a casting call for a clown to make personal appearances to promote the Bozo records. After landing the job, he took over as the voice on the records and then bought the rights to the character.
Harmon launched the first Bozo children's show on KTLA-TV Channel 5 in Los Angeles in 1959, with Pinto Colvig's son, Vance, playing the role.
From there, Harmon began franchising Bozo, and the bulb-nosed clown with the big feet became an iconic children's show character around the nation and the world.
Harmon trained more than 200 men to portray the carrot-topped character on TV, including future "The Today Show" weatherman Willard Scott and Los Angeles television weatherman Johnny Mountain.
In the mid-1950s, Harmon launched Larry Harmon Pictures Corp., which turned out animated cartoons featuring not only Bozo but also Popeye, Mr. Magoo, Dick Tracy and Laurel and Hardy (Harmon acquired the rights to the comedy duo in 1960.)
His company continues to license the names and characters of Bozo and Laurel and Hardy worldwide.
A Harris poll once recognized Bozo as the world's most famous clown.
"Bozo is a combination of the wonderful wisdom of the adult and the childlike ways in all of us," Harmon told the Associated Press in 1996. "Bozo is a star, an entertainer, bigger than life. People see him as Mr. Bozo, somebody you can relate to, touch and laugh with."
In 2004, Harmon and Bozo were in the news when the International Clown Hall of Fame in Milwaukee announced it was revoking its Lifetime of Laughter Award given to Harmon in 1990 as Bozo's creator, and posthumously inducted Pinto Colvig as the first Bozo.
Kathryn O'Dell, the hall's executive director, told the Associated Press that the hall had been duped into believing that Harmon created Bozo and did not discover the truth until Buck Wolf, an ABCNews.com columnist and entertainment producer, reported that Harmon was wrongly laying claim to the character.
Harmon told AP he was saddened that the hall had removed his plaque and denied having misrepresented Bozo's history.
"Isn't it a shame the credit that was given to me for the work I have done -- they arbitrarily take it down, like I didn't do anything for the last 52 years," he said.
He said he had always acknowledged that Capitol Records writer/producer Alan Livingston created Bozo.
But, Harmon said, he created Bozo's personality and image as they are known today.
"What I created for the world," he said, "was me and my image: what I sound like, what I look like, what I walk like, what the costume looked like."
Born in Toledo, Ohio, on Jan. 2, 1925, Harmon was raised in Cleveland. After serving in the Army during World War II, he moved to Los Angeles to attend USC, where he majored in theater and was drum major in the Trojan marching band.
At USC, he started acting in radio and movies and, in the early 1950s, he starred in the "Commander Comet" TV series.
In addition to his wife, Harmon is survived by his son, Jeff; his daughters, Lori Harmon, Marci Breth Carabet, Ellen Kosberg and Leslie Breth; and four grandchildren.
Funeral services are pending.