The 21-year-old actress is currently shooting the fantasy movie and left the Hollywood hunk with a black eye and a "big lump on his nose" after a fight scene went wrong.
In an appearance on 'The Tonight Show with Jay Leno', Kristen - who is playing the titular character - revealed: "Girls, if you've ever wondered if it works, it works! I was supposed to miss him but I basically knocked him right out of his close-up."
The 'Twilight Saga' star - who has been pictured with scraped and bruised knuckles this week - also revealed she won the sought after part after a "really intense, four-hour" meeting with director Catherine Hardwick.
Kristen - who is dating Robert Pattinson - added: "I hadn't read the book when I accepted the part. It was crazy."
In the movie, Kristen plays Snow White and is trying to escape the clutches of the evil Queen Ravenna, portrayed by Charlize Theron, who wants to eat her heart so she will become immortal.
Chris, 28, is playing Eric, the Huntsman in the movie - which is due for release in June 2012.