Siegel, who continued to work until two weeks before his death, died in New York after a long battle with colon cancer, ABC News said.
The mustachioed Siegel, who joined "Good Morning America" in 1981, was remembered by his ABC News colleagues for his wit and passion for the arts.
"Joel was an important part of ABC News, and we will miss him," ABC News President David Westin said in a news release. "He was a brilliant reviewer and a great reporter. But much more, he was our dear friend and colleague."
ABC anchor Charles Gibson described Siegel as "brilliant" and "a man of impeccable taste."
"When Joel came into your office to talk about anything -- it was going to be interesting and you were going to learn something," Gibson, former co-anchor of "Good Morning America," said on the ABC News website. "He had an inexhaustible supply of stories -- most funny, many poignant, all with a point or a punch line."
As entertainment editor for "Good Morning America," Siegel interviewed scores of celebrities such as Paul Newman, Halle Berry, Brad Pitt, George Burns, Gene Kelly, Jack Lemmon and all four of the Beatles. His annual Oscar broadcast, "Joel Siegel's Road to the Academy Awards," aired for 10 years on WABC-TV and also was syndicated.
For his television work, Siegel received five New York-market Emmy Awards. He also co-wrote the book for the 1981 musical "The First," which earned him a Tony nomination.
Siegel was 54 when doctors informed him that he had colon cancer in 1997, shortly after he learned that his third wife, artist Ena Swansea, was pregnant and he was going to be a first-time father.
Concerned that he may not live long enough for his young son to get to know him, Siegel wrote the 2003 memoir "Lessons for Dylan: From Father to Son."
"I was in my 50s when Dylan was born, so even in the best of times I couldn't expect to spend more than a score or so of years with him," Siegel told the Chicago Jewish News in 2003. "And it hasn't been the best of times, not with three cancer surgeries and chemo and CAT scans and six months of radiation in the past five years."
In 1991, Siegel co-founded (along with actor Gene Wilder and others) Gilda's Club, a nonprofit organization that operates facilities offering emotional and social support for cancer patients and their friends and families. He also testified before Congress on behalf of cancer patients.
Born in Los Angeles on July 7, 1943, Siegel graduated cum laude from UCLA in 1965 with a degree in history.
While at UCLA, he registered voters in Georgia and marched with the Rev. Martin Luther King Jr. "I was a civil rights worker and I'm really proud of that," he wrote to his son in his memoir.
Siegel, who served in the Army Reserve from 1967 to 1973, wrote jokes for Sen. Robert F. Kennedy (D-N.Y.), freelanced for publications such as Rolling Stone and Sports Illustrated, wrote book reviews and stories for the Los Angeles Times and worked as a copywriter and producer for an advertising agency.
After arriving in New York in 1972, he worked as a feature reporter for WCBS-TV and hosted "Joel Siegel's New York" on WCBS Radio. In 1976, he became the entertainment critic for WABC-TV.
The first movie he reviewed on the air, he told the Tulsa World in 2004, was "Magic," starring Anthony Hopkins as a ventriloquist.
"So I went and got a ventriloquist dummy and did the review, with me saying I liked the movie, and the dummy saying how he hated it," he recalled.
"So I got to do another review the next day. And I've kept that in mind, that every day is really an on-air audition."
He is survived by his son and wife.