Busta Rhymes Gushes Over Janet Jackson After 25-Year Reunion Onstage

Busta Rhymes says a highly-anticipated reunion with Janet Jackson for their 1998 song together was well worth the wait -- and right on time too ... almost like it was divine!

The legendary rapper was gushing about JJ Tuesday night ... this shortly after they shared the stage at Madison Square Garden, where she was putting on a crucial show that's part of her larger 'Together Again' tour -- which couldn't be more perfectly named.

Indeed ... Busta got on the mic with Janet to crank out their hit, 'What's It Gonna Be?!' -- a fan fave, and something folks have wanted to see them perform together live for years now.

That's certainly what BR has wanted as well ... and he talked to a photog about just how big of a moment it was for him. As it turns out -- the dude, who's no stranger to being in front of audiences, says he was actually shaking in his boots ahead of their big duet onstage.

He actually suggests something happened up there that gives away the fact he was freaking the hell out -- we have video of the performance ... so take a look for yourself.

Anyway, it's clear that this was big for Busta and that he's grateful for the opportunity to have done it now -- even if it is 25 years later. He says any sooner wouldn't have been as significant ... so, in his mind, this coming together with Janet was right on time.

BTW, he also gets into the story about how he first linked up with her to record way back when -- and even that tale sounds too good to be true. Busta remembers it like it was yesterday.

As he notes, the reunion marks a cultural snapshot that transcends music. And, considering Janet's theme for the tour is in this ballpark, there's probably more stuff like this coming.