A woman who claims she launched Puff Daddy's career is suing the hip-hop mogul for $12 million -- claiming he fired her from his Bad Boy record label because she was old and disabled.


Francesca Spero just filed a lawsuit in federal court in NY -- in which she describes herself as a "51-year-old white woman" who served as a high ranking exec for Diddy since 1998.

In the docs, Spero claims she and Diddy -- aka Sean Combs -- butted heads after she informed him that she needed major hip surgery in 2008 ... and then later "suffered a relapse" to an addiction to prescription medication and alcohol.

According to the docs, Spero claims Diddy was "unsympathetic to her condition" -- and ultimately tried to freeze her out of the company.

Spero says she continued to do her work -- signing new artists -- but was eventually fired in March
2010 ... and replaced by a woman 10-15 years younger who "lacked the skill set and experience Spero brought to the position."

Spero now claims Diddy -- along with his publishing and management companies -- owe her $12 mil in damages for age and disability discrimination.