The death was announced by Ms Harper’s family, though the cause has not been announced. Ms Harper also appeared in ‘Rhonda’, a spinoff from ‘The Mary Tyler Moore Show’. She won a Golden Globe and four Emmys for her performance in the two programmes during the 1970s.
Ms Harper was known to be battling incurable cancer in the membrane around her brain.
In January 2013 she was diagnosed with leptomeningeal carcinomatosis and given just three months to live.
However eight months later she reported the cancer was near remission.
Ms Harper discussed her condition during an appearance on US TV show ‘The Doctors’ in March 2013.
She commented: “I’m a big mouth.
“I really want Americans and all of us to be less afraid of death, know that it’s a passage.
“But don’t go to the funeral before the day of the funeral. While you’re living, live.”
Ms Harper also had a tumor removed from her right lung in 2009.
READ MORE: Valerie Harper: ‘I am not cancer-free’
She continued acting after hit show ‘Rhonda’, appearing in the NBC sitcom ‘Valerie’ in 1986.
However she left at the end of the second series following a salary dispute with the production company.
She was later awarded $1.4million (£1.14million) in damages following a legal battle.
In 2013 Ms Harper was a contestant on ‘Dancing with the Stars’ before being voted off after a month.
She also appeared in the 2017 short film ‘My Mom and the Girl’ and did voice work for hit comedies ‘American Dad!’ and ‘The Simpsons’.
Ms Harper married her first husband, actor Richard Schaal, in 1964.
They divorced in 1978, after which she married Tony Cacciotti in 1987.
The couple would go on to adopt a daughter.
Ms Harper began her career as a dancer on Broadway, before moving on to acting.