Tony Bennett, the smooth American singer who had an enduring hit with I Left My Heart in San Francisco and remained perpetually cool enough to win over younger generations of fans well into the 21st century has died, his publicist says.

Bennett was 96. He died at his home in New York City on Friday (local time) of age-related causes, his publicist Sylvia Weiner said in a statement.

No less than Frank Sinatra called the former singing waiter “the best singer in the business” after he became a star in the 1950s. Bennett went on to win 20 Grammy awards, including a lifetime achievement award.

The older he grew, the more diverse his collaborators became. Bennett was in his late 80s when he recorded a 2014 album of duets with the outre Lady Gaga and went on a world tour with her in 2015.

Partners on his popular Duet albums ranged from former Beatle Paul McCartney and soul queen Aretha Franklin to country star Willie Nelson and U2’s Bono.

Bennett marked his 90th birthday in 2016 with a party in New York that drew celebrities such as Bruce Willis and John Travolta. The Empire State Building put on a light show in his honour. He also published a memoir in 2016 titled Just Getting Started.

Bennett revealed in early 2021 that he had been diagnosed with Alzheimer’s disease in 2016. He kept recording after the diagnosis and later tweeted, “Life is a gift — even with Alzheimer’s.”

Due to his illness, Bennett retired from performing after his final concert at Radio City Music Hall On August 3 and 5, 2021.

Lady Gaga and Tony Bennett perform at the Grammy Awards in 2015. Photo: Getty

Bennett’s career was filled with highs and lows.

Discovered by Bob Hope who saw him singing in New York’s Greenwich Village and made him an opening act on his TV show, Bennet became one of the most popular singers of the 1950s before the rise of rock’n’roll undermined him.

As the rock era began, Bennett moved away from pop songs toward jazz, pulling his material from the works of writers like Cole Porter, Johnny Mercer, George and Ira Gershwin and Richard Rodgers and Lorenz Hart.

In the next phase of his career, Bennett recorded I Left My Heart in San Francisco in 1962. It reached only No. 19 on the Billboard chart but became his signature song.

“People ask me, ‘Don’t you get tired of singing that song about San Francisco?'” Bennett said in a Reuters interview.

“I say, ‘Do you get tired of making love?'”

He was in his 50s in the late 1970s when he found himself facing a decaying marriage, a cocaine habit, a multimillion dollar tax debt and limited career prospects.

He pulled out of it by turning over his management to his son Danny, who propelled his father to new heights of popularity by introducing him to younger generations. He would regularly appear on MTV and won album of the year at the 1995 Grammys.

Bennett released three albums of duets in 2006, 2011 and 2012, which featured collaborations with younger stars singing old classics, and an album with Lady Gaga in 2014.