Preston had been in a deep coma since Nov. 21 after hypertension caused kidney failure among other complications, FoxNews.com reported Tuesday.
Preston accompanied Britain's Fab Four on "Let It Be," "The White Album" and "Abbey Road." He was the first act signed to the Beatles' Apple Records label, which spawned his album, "That's the Way God Planned It."
His keyboards can be heard on the Rolling Stone' "Miss You" and he was a collaborator with Eric Clapton and Sly & the Family Stone as well.
He also recorded with Neil Diamond and the Red Hot Chili Peppers in recent years, FoxNews.com said.
Among Preston's own hits were "Nothing From Nothing" and "Will It Go Round in Circles." Joe Cocker scored an international hit with Preston's "You Are So Beautiful."