Cameron Diaz in Diane von Furstenberg

Whitney Port in Yigal Azrouel

Paris Hilton in Blumarine

Vanessa Hudgens in Jenny Packham

Sandra Bullock in Oday Shakar

Victoria Justice in BCBG Max Azria

Nikki Reed in Miu Miu

Scarlett Johansson in Dolce & Gabbana

Miranda Cosgrove in Versus by Versace

Katy Perry in Zuhair Murad

Aubrey Plaza in unknown

Eva Mendes in Stella McCartney

Anna Kendrick in Zac Posen

Kristen Stewart in Dolce & Gabbana

Best dressed? Sandra Bullock, Whitney Port, and Paris Hilton. MTV Movie Awards is about fun with fashion so well played, ladies.
Source: MTV, Fabsugar, and Just Jared