Brian McKnight Says Kobe Song Will Be on His Final Album

Brian McKnight's touching personal tribute to Kobe Bryant will make its way to the public eventually on a new album -- and just as sad ... it might be his last foray into music.

The R&B singer was on "TMZ Live" Monday to talk about writing the new tune, "Can't Say Goodbye" ... which he personally wrote and performed in honor of the late NBA superstar. He says he can't even remember writing it ... the lyrics just poured out of him.

Brian tells us he's never seen a death affect the world the way Kobe's did -- and that's taking MJ and Prince into consideration. To him, it just proves Kobe was THAT beloved.

He also told us, he'd gladly perform "Can't Say Goodbye" at Kobe's memorial service, if asked. We also asked him about releasing the track to the public -- and that's when he dropped a bombshell about his more than 30-year career. Brian says it's about to be a wrap, at least in the studio, after one more album ... which will include the Kobe tribute.

As for how serious he is about retirement -- we pressed Brian, and on a scale of 1 to 10 ... sounds like he's squarely a Cher.