The TV actor and musician reportedly suffered a heart attack after playing sports with his teen son Carter.
Thicke, who is the father of Blurred Lines hitmaker Robin Thicke, is said to have suffered an attack while he was playing hockey with the 19-year-old.
The Canadian was rushed to Providence St. Joseph's Medical Center on Tuesday afternoon and was pronounced dead, according to TMZ.
Thicke, who has three sons – Robin, Brennan and Carter – is also survived by his wife Tanya.
His death was confirmed by his son Robin's publicist.
Alan's sudden passing has been confirmed. At present, we have no further details," Monique Moss said in a brief email, according to Reuters.
The all-round entertainer and composer was behind the theme tune for Diff'rent Strokes, Wheel of Fortune and Growing Pains.
He also starred in the sitcom as Jason Seaver on the ABC series.
As well as game shows and talk shows, the talented entertainer's most recent role was in the Netflix reboot for Fuller House.
Just hours ago he tweeted about the second season, as he wrote: "Season 2 Fuller House looking good. I even like the ones I’m not in! fullerhouse".
He was recently awarded the Icon award at Whistler Film Festival, he thanked the organisation earlier today, as he wrote: "Thanks to Whistler Film Fest for the Icon Award. I promise to try and stay iconic."
Thicke came to US television after having risen to prominence as a host and frequent talk-show guest in his native Canada.
Prior to Growing Pains, he hosted a short-lived syndicated late-night talk show, Thicke of the Night, that was one of the first efforts at challenging the dominance of NBC's The Tonight Show.
Born in Kirkland Lake, Ontario in 1947, Thicke attended the University of Western Ontario after graduating from secondary school. He hosted a game show, First Impressions, in Canada, as well as a talk show, The Alan Thicke Show.