The musician, who has passed away at the age of 72, will be best remembered for the 'Everlasting Love' hit which was once covered by U2.
'Everlasting Love' was actually Robert's first single all the way back in 1967. It was written by label owners Buzz Cason and Mac Gayden.
The song reached number 14 on the US R&B chart and 13 on the Billboard Hot 100.
He followed this up with two further hits 'Blessed Are The Lonely' and 'Isn't It Lonely Together'.
His last back hit single in the charts was all the way back in 1974.
But there was a renewed interest in his music when U2 covered 'Everlasting love' as a B-side for their single 'All I Want Is You' in 1989.
Despite not having any more chart success, he still continued to sing. And according to Wikipedia, he worked as for "Vanderbilt University as a chemical lab technician, a chemistry teacher, and a member of the grounds crew"
He died at home in Tennessee on 5 November. RIP