Minaj won her first VMA last year in the 'Best Hip-Hop Video' category for 'Super Bass', besting fellow nominees Chris Brown, Lupe Fiasco, Lil Wayne and Kanye West.
Speaking to MTV News, the singer cited the award win as one of her proudest accomplishments.
"I remember when I won for 'Super Bass'," Minaj explained. "It had gotten to the point where I never won anything, so I would just go to awards shows just to wear a cute outfit. So when they called my name, I was like, 'Is this a joke? What? Is this really happening?'"
She continued: "That was like, a very, very memorable moment. That was one of the best moments in my career, to just hear my name and truly be surprised."
Minaj is nominated in multiple categories again this year, including 'Best Hip-Hop Video' for 'Beez in the Trap' and 'Best Female Video' for 'Starships'.
The popstar will also perform with a surprise guest on the awards show.
Kevin Hart hosts the 2012 MTV Video Music Awards, airing live from the Staples Centre in Los Angeles tonight (September 6) at 8/7c.
> MTV Video Music Awards 2012: The nominees in full
Watch Nicki Minaj's 'Beez in the Trap' music video below: