The 18-year-old actress was joined by her Happyland co-star Bianca Santos on the red carpet.
Before the show, Katherine took to Twitter to tell fans how psyched she was for the big bash.
“Just arrived at the @MTV #VMAs – it’s going to be an amazing evening,” she tweeted.
FYI: Katherine is wearing an Alice and Olivia dress and Aldo shoes. Bianca wore a Naeem Khan dress and Casadei shoes with One Jewelry earrings.