Steinfeld said on "The Early Show" Friday morning she fell in love with the part.
"I loved the material, the role itself, and the film overall, the story," she said. "... And it was the first time going in reading for this that I could say to myself, I was 110 percent prepared and ready to go and show that."
Steinfeld, who has limited acting experience, found herself working alongside two Oscar winners, Jeff Bridges and Matt Damon.
She said she was prepared for the role after years of study.
"I haven't had too much experience and haven't done a lot of onscreen stuff," she said. "But I've been studying for six years, studying acting and taking classes and everything. Honestly, I think that all those years of hard work kind of paid off with this."
Her hard work has led to some unique opportunities. In fact, she'll be presenting at the Golden Globes with Justin Bieber. Steinfeld, a big fan of Bieber, said she's not great with crowds, but said she hopes she can walk away with his autograph after the experience.
For more with Steinfeld -- including how much money she made on a "swear jar" on the "True Grit" set -- click on the video below.