Fiddy joined NM on stage during her show at Madison Square Garden Saturday night -- and he used his moment in the spotlight to call out his love for "sex workers" ... a clear dig at his baby mama.

He said the phrase quickly on the mic, but the audience heard it … and got a kick out of it too, it seems.

Remember, Daphne Joy was alleged to have been one of Diddy’s "sex workers” in Rodney Jones' recently amended lawsuit. The accusation caught the eye of 50, who shares 12-year-old Sire with DJ ... prompting him to put the model on blast on social media.

Daphne Joy responded to 50's shade by alleging the rapper abused and raped her during their relationship -- which 50 has vehemently denied. FWIW, Daphne herself has denied the “sex worker” allegation as well.

There's no doubt 50 was directly referring to the Diddy drama with his comment last night. After sharing footage from his special appearance at MSG … he took to X and declared Nicki was "no P. Diddy."

He added ... "I’m not gonna front Nicki got all the bitches! I looked in the crowd and was like damn baby what you doing? Then threw my jacket at these little sex workers. LOL."

He also shared his "sex workers" comment from Saturday on Instagram ... repeating his sentiment in the caption.

50 and Daphne seem to be gearing up for an all-out custody war — he said he’d be seeking sole custody of their kid … this as the Diddy fallout continues to take shape.