The gorgeous co-stars made for a very glamorous pair as they posed for cameras at the Lincoln Centre in Manhattan on Monday, 15 December.
Bradley and Sienna play a married couple in American Sniper, which is based on the autobiography of US Navy SEAL Chris Kyle.
It's directed by Clint Eastwood.
Earlier this year, we saw Bradley bulk up considerably for the role, putting on around 40lbs ahead of filming. He's said in past interviews he wanted to be as physically like Chris as possible.
Bradley's now back to his svelte best as we saw last night while he shared laughs with Sienna on the red carpet.
British actress Sienna looked gorgeous (as usual) in a white off-the-shoulder dress with sheer detail that gave us all a glimpse at what was beneath!
After the red carpet, the movie's cast and crew moved on to an after party, where Bradley's model girlfriend Suki Waterhouse also joined in the fun, chatting with fellow fashionista Sienna.
American Sniper arrives in cinemas 16 January.