The Notorious B.I.G.'s mom is PISSED Kendall and Kylie Jenner slapped their portraits over her son's image just to peddle t-shirts.

Biggie's mom, Voletta Wallace, posted a photo of one of Kendall and Kylie's new "Vintage T-Shirts" which launched on their site Wednesday. Voletta ripped the biz move as "disrespectful and exploitation at its worst" -- and not just against her son.

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Voletta's also pissed about another shirt that features Kendall's face over a Tupac image.

Kendall and Kylie were selling at least 3 of these type of shirts with Pac and Biggie ... at $125 a pop.