Diddy chose to do the right thing over money -- evidenced in the fact that he turned down a fortune to make sure his former artists have control of their own music .. TMZ has learned.

Sources with direct knowledge tell us the media mogul and Bad Boy label honcho is making an unprecedented move in the music industry right now -- namely, handing over the publishing rights to several of his former BB acts ... and forsaking a lot of cash to do so.

Word of this started to percolate just a few days ago, when Cam'ron took to social media to announce that Ma$e had finally sealed the deal with Puff and secured his catalog for himself.