The Hunger Games actress debuted her new look on her Facebook page on Wednesday afternoon.
The Oscar-winner revealed the long-on-top, side-swept elfin hairstyle while she sat on a plane ahead of an event.
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"Headed up north for #GLOBALFANDAY with The Hunger Games Catching Fire cast," the 23-year-old wrote. "Follow this page all day for updates!"
Although some fans initially thought the new 'do might have been a wig, another photo that she posted shortly afterwards seemed to confirm that the sophisticated new look is here to stay.
This isn't the first time that the Silver Linings Playbook actress' hair has caused a buzz.
Jennifer chose to chop her shoulder-length hair into a shorter, blonder bob with a sweeping fringe just hours before a red carpet appearance back in April.
She isn't the only famous Jennifer to have changed her hairstyle this week.
Jennifer Aniston revealed that damage caused by a Brazilian blowdry forced her to cut around six inches off her hair.
I actually just cut all my hair off two days ago," she said during an interview with Elle.
"My hair did not react really well to it," she added, referring to the Brazilian blowdry.
"The minute I cut my hair I want it back. Always . It’s a guarantee. I'm trying really hard to love this one."
She also revealed to Vogue that she had chopped her trademark locks. "It was kind of spur-of-the-moment.
"I was flipping through the television channels and I paused it to take a picture and I sent it to Chris [McMillan, her hair stylist], and he said, 'That's Lawren Howell from Vogue!' And then he said, 'I just cut that!' So that's it."
Brazilian blowdries have been widely praised for banishing frizz and leaving locks silky smooth, but many contain chemicals which can damage the hair.
See our gallery of celebrities with short hair