"I've kept my mouth shut, but now you're lying about me", she tweeted.
The rapper got his first ever Grammys nod for his fifth and final studio album, with news of his nomination being revealed just three weeks after his death in September a year ago from an accidental overdose.
Her late ex-boyfriend Mac Miller tragically died previous year from an accidental overdose.
She won the best pop vocal album trophy for Sweetner beating Taylor Swift, Kelly Clarkson, Pink, Shawn Mendes and Camila Cabello.
The 'thank u, next' singer took to Twitter to write "trash", followed by "bullsh*t", after the award was announced. Following an opening from a pianist, Cardi emerged in a sparkly black jumpsuit while strutting her stuff like a showgirl.
She accessorised her look with white gloves which featured long tassels falling from the garments.
She thanked him in her acceptance speech, as well as their seven-month-old daughter, Kulture. "Maybe I need to start smoking weed".
Shortly after Cardi accepted the award, Grande hopped on Twitter to call the decision "literal bullshit" and "trash".
Cardi was escorted on stage by her husband Offset and it took her a couple moments to catch her breath and realize that she just won.
Offset's debut album will come two months after The New York Times reported it would be released: on the rapper's 27th birthday, December 14.