ET's Nischelle Turner caught up with Steinfeld on the carpet, who dished on making the transition from movies to music.
"The idea of performing and entertaining [was already there]. I started with both [acting and singing] around the same time," she shared. "The acting kind of happened first, and the music was more of a side project until I did that little movie called Pitch Perfect 2, which gave me the opportunity to go into music, which I've been doing the last few years and I'm obsessed."
Steinfeld just released her new single, "Most Girls," which she said came from a combination of her thoughts, feelings and experiences.
"It's a pop song. I always love when I can take my thoughts, my feelings, my experience to my friends who are amazing writers and turn it into a pop song," she explained. "It's always great to work with friends, it obviously never feels like you're working."
One special member of Stenfeld's squad is Taylor Swift. See more on the pair's friendship in the video below.