Rivers, 81, had been on life support in Mount Sinai Hospital following a cardiac arrest in New York last week.
In a statement, her daughter, Melissa, said she died surrounded by family and friends.
She thanked hospital staff for their care.
The comedian, best known for her lacerating wit, stopped breathing during a procedure on her vocal cords at an outpatient clinic last Thursday.
“It is with great sadness that I announce the death of my mother, Joan Rivers,” Melissa said.
“She passed peacefully at 1.17pm surrounded by family and close friends.
“My son and I would like to thank the doctors, nurses, and staff of Mount Sinai Hospital for the amazing care they provided for my mother.”
Melissa continued: “My mother’s greatest joy in life was to make people laugh. Although that is difficult to do right now, I know her final wish would be that we return to laughing soon.”
The actress and stand-up comedian is well known for her legendary put-downs and has more recently turned her razor-sharp tongue on the red carpet’s worst dressed celebrities, hosting the E! network’s Fashion Police.
Both Rivers and Melissa, her only child, have appeared together in reality TV show Joan & Melissa: Joan Knows Best?
She didn’t just fire her barbs at others, however. She was always prepared to joke about herself, and in particular her plastic surgery.
In 2010, she tweeted a joke about her death, saying: With all the plastic surgery I’ve had I’m worried that when I die, God won’t recognize me!
Shortly after her death was announced, tributes poured in from the world of entertainment.
Comedian and actress Whoopi Goldberg tweeted: “My friend Joan Rivers has passed away once again to quote Billy Crystal… There are no words. Bon Voyage Joan.”
TV show host Ellen DeGeneres described Rivers as a pioneer, adding: “She paved the way for a lot of comedians. I’m very sad she’s gone.”
Born Joan Alexandra Molinsky in Brooklyn, New York, to a family of Jewish immigrants who had fled the Russian Revolution, Rivers’ big break came in 1965 when she appeared on The Tonight Show Starring Johnny Carson, and a long television career followed.
Her first marriage lasted only six months but her second with Edgar Rosenberg spanned more than two decades until his suicide in 1987.