The mourners included radio host Howard Stern, actress Sarah Jessica Parker, mogul Donald Trump, comic Kathy Griffin and film star Whoopi Goldberg.
Crowds of fans and media also gathered outside Manhattan's Temple Emanu-El.
The comedian, who died on Thursday, wrote in 2012 about how she wanted her funeral to be "a huge showbiz affair".
Rivers died a week after suffering a cardiac arrest while having a routine medical procedure. She was 81.
Howard Stern delivered the eulogy, describing Rivers as "the best friend in the world... a big sister... a crazy aunt at a bar mitzvah", according to People magazine.
Other speakers included Rivers' daughter, Melissa, TV journalist Deborah Norville, friend Margie Stern and New York Post columnist Cindy Adams.
Actor Hugh Jackman delivered a rendition of the song Quiet Please, There's a Lady on Stage, from his musical The Boy From Oz, and Broadway actress Audra McDonald sang Smile.
The New York City Gay Men's Chorus opened the ceremony with a series of Broadway hits, while bagpipers from the New York City Police Department performed New York, New York.
Other mourners included Rivers' former Fashion Police co-star Kelly Osbourne, actors Alan Cumming and Tommy Tune, music producer Clive Davis and fashion designers Carolina Herrera and Michael Kors.
US TV personalities including Barbara Walters, Geraldo Rivera, Diane Sawyer, Kathie Lee, Hoda Kotb and Andy Cohen also paid their respects.
The outspoken star wrote in 2012 about her funeral plans. "I want paparazzi and I want publicists making a scene!" she said. "I want it to be Hollywood all the way. I don't want some rabbi rambling on; I want Meryl Streep crying, in five different accents."
Hundreds of fans gathered to observe proceedings outside the temple. "I watched her growing up," Sharon Herstein, from New York, told Reuters. "She made me laugh. Her success carries women across all industries."
Max Buccini, 30, said: "What she did for the gay community has been so impactful and generous. She always delivered. She knew her audience. She was a pioneer in the entertainment industry and just a trendsetter,"
Meanwhile, in what The Sunday Times billed as her final interview, she said she had given her daughter Melissa strict instructions on who should not be allowed to attend her funeral - but did not say who was on the list.
Rivers also said she had been preparing Melissa for her death. "It's like, God, I'm in my 80s," she said. "Nobody, when I die, is going to say, 'How young?' They're going to say, 'She had a great ride.'"
After her passing, tributes for the comedy queen flooded in from figures including David Letterman, Ellen DeGeneres and Prince Charles, who praised her "unstoppable sense of humour and... enormous zest for life".
Senior Rabbi Joshua M Davidson, who conducted the service, said beforehand in a statement: "We mourn with her family, friends and all those millions to whom she brought laughter and joy."
Rivers stopped breathing during a procedure on her vocal cords at an outpatient clinic on 28 August. The New York City Medical Examiner's Office said that after an initial examination, further tests would be carried out to determine the cause of death.