The announcement was made by Irwin Winkler at an event in L.A. Saturday -- where he confirmed that not only is 'Creed IV' happening ... but saying Mike would be back in the director's chair, and obviously starring of course.

According to Deadline, Winkler said they'd start circling the project sometime in 2024 -- with him explaining, "We have a really good story [and] a really good plot. We got a little delayed because of the strikes, but about a year from now we’re going into pre-production."

Considering how much of a moneymaker "Creed III" was, this is great news for MBJ ... but probably hits a nerve with Sly -- who's slammed IW and his handling of the 'Rocky' rights.

As we reported ... Stallone has called on Winkler to give him an ownership stake in the IP -- of which he has no control over, apparently, after having sold the rights to the OG script years ago. Sly's POV is ... he's the creator of the character/story, so he should have a cut.

It goes without saying ... Rocky himself was not featured in the latest film -- and Sly said he just didn't like direction Mike and Irwin were taking things ... although he did wish 'em well.

Sly's love of his baby ('Rocky') actually just got a renewed focus thanks to a great Netflix doc on the man himself, "Sly" ... which touches heavily on how the Oscar-winning film came together. If you watch it, you'll see all things 'Rocky' are still very near and dear to SS.

Interestingly enough, Sylvester doesn't address Winkler in the doc (directly or indirectly) but he's made his feelings about the issue very clear. For now, it doesn't appear he's going to be involved with 'Creed IV' ... although MBJ left the door open in interviews earlier this year.