Mase outlined his rap career of ‘mo money, mo problems’ during a new interview with Gillie Da Kid and Wallo's “Million Dollaz Worth of Game” podcast, unloading about his gripes with ex-friend Diddy in the process.

The former Bad Boy rapper removed his designer sunglasses and admitted “he was trying to be nice” while getting his point across, but went on to paint himself as an errand boy during his early time with the label.

According to Mase, he initially didn’t get paid for being a part of Diddy’s 1997 No Way Out Tour (despite appearing on several album tracks) … and also claims Puff shortchanged his royalty credits — including writing and co-producing the late Notorious B.I.G.’s monster hit “Mo Money, Mo Problems.”

Mase claims he told Stevie J how to arrange the track, which samples Diana Ross’ “I’m Coming Out,” while Diddy was out partying ... but still slapped his name on songs because he owned them, and he was the boss.

Mase also addressed Fivio Foreign’s claims the “City of Gods” rapper was swindled into signing a record deal for a paltry $5,000 bonus.

According to Mase, Fivio’s claims of being low-balled were “reckless” … alleging he negotiated the contract so they both made out with $800K and $700K from label partner Columbia Records.

Mase also says he allowed Fivio Foreign to keep his publishing rights, meaning he can decide to place his music wherever he wants -- for example, advertisements -- for profit.

The full episode plays out like a cautionary tale for all upcoming artists -- know what you're signing when it comes to that dotted line!!!

Diddy and the fam are currently on a vacation (Stevie J is there too!) so there’s no telling when or if he'll respond -- but a couple of weeks ago, Momma Combs warned Mase not to throw mud on her son’s name.

Obviously, he didn’t listen. There may be hell up in Harlem, soon!!!