Best known for the 1972 hit "Me and Mrs. Jones," Paul helped define Philadelphia Soul and modern R&B. Paul's music career spanned nearly six decades.
Paul topped the charts in 1972 with the classic "Me and Mrs. Jones," a ballad about an extramarital affair that won him a Grammy Award. The single sold more than two million copies and made him famous internationally.
Born in Philadelphia as Paul Williams, he grew up in the city as it became a center of smooth, funky and jazzy melodies.
Paul's melodious voice made him "one of the great artists to come out of Philly and to be celebrated worldwide," his producer Gamble and Huff said in a statement late Sunday.
"Our proudest moment with Billy was the recording of the salacious smash 'Me and Mrs. Jones.' In our view, it is one of the greatest love songs ever recorded," they said.
After "Me and Mrs. Jones," Paul came out with "Am I Black Enough for You," which at the time stirred controversy for its allusions to the Black Power movement. He would later say the song was before its times.
He went on to produce numerous songs and continued performing up until his death.
Paul died on Sunday in New Jersey after battling cancer. He had two children and left behind his wife Blanche Williams.
cw/kms (AFP, AP, dpa)