The actress stars in The Perks of Being a Wallflower, in which she shares a raunchy kiss with fellow actor Logan Lerman.
The 22-year-old explained that she was so moved by the script that she knew she was going to have to make it extra special on set.
She told MTV News: "I mean, when I read our first kiss scene, it's so epic. It's like the most beautiful scene I've ever seen written on a page.
"And it was like, 'Oh, we're going to have to kill this one!' Like, it's so good, I wanted to do it justice.
"And it's so emotional and we're both so vulnerable in it, but the main thing was I get to do it with Logan.
"He makes me feel so safe, so it's going to be fine, which made it fine."
Despite Logan making Emma feel comfortable during filming, he admitted that he was nervous about kissing in front of the crew.
He said: "[It was] nerve-racking. Those scenes are always hard to do when there's 15, 20 other people in the room."
Watch a trailer for The Perks of Being a Wallflower below: