She was best known for her television roles in the 1960s sitcom The Dick Van Dyke Show and the eponymous The Mary Tyler Moore Show in the 1970s.
She was also nominated for a best actress Oscar in 1980 for the film Ordinary People.
Mara Buxbaum said in a statement she died in the company of friends and her husband, Dr S. Robert Levine.
Born in Brooklyn, New York, Moore moved to Los Angeles when she was eight years old and started her career in show business as a dancer aged 17.
Her first appearance was in a Hotpoint advert in the 1950s, dressed as an elf.
But her parts grew in size during that decade, before she landed the role of wife Laura Petrie in The Dick Van Dyke Show in 1961.
Later, she starred as TV producer Mary Richards in her self-titled sitcom. Running for seven seasons from 1970 to 1977, it was named by Time Magazine as one of 17 shows that "changed television".
Moore emerged onscreen at a time when women in leading roles were traditional housewife characters.
But with her modern trousers and Jackie Kennedy-style hair, she challenged the stereotype in front of millions of viewers.
US Emmy award-winning actress Mary Tyler Moore has died aged 80, her publicist says.