The Hunger Games star is famous in the movie franchise for her dark long hair, and is often seen on the red carpet with a more honey-hued 'do.
She did the Big Reveal on Facebook, writing: "Headed up north for #GLOBALFANDAY with The Hunger Games Catching Fire cast. Follow this page all day for updates!"
The Hunger Games: Catching Fire Global Google+ Hangout Q&A was streamed live on Google, and fans were kept updated on Jen's Facebook page.
Commenting on the new hairdo, Jennifer first joked that she did it to annoy the director of The Hunger Games, Francis Lawrence.
According to the Daily Mail, she said: "I just did it to make Francis mad. I did it just to annoy him. He totally thought it was me giving him the finger.
"But it's not. It's just fried from being dyed so much."
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