Here are all the details about how she rang in her new year.
But let's be real — girl definitely doesn't look like the grandparent she is. Between her fit figure and long luscious locks, she was a sight to be envied during the festivities.
Though Jenner partied with her friends and family on Tuesday, this birthday was her first since she began her public transition to becoming a woman. The Los Angeles event was also to mark the launch of Logo TV's Beautiful As I Want To Be web series, but all eyes were on Jenner.
Jenner told People that she got to share her "first" birthday with a couple of her daughters on Tuesday, but didn't specify which ones or how they celebrated, but we know that Kim and Kourtney Kardashian, along with Kylie Jenner, were in attendance, thanks to their Instagram pics.
Jenner's friends and fellow transgender advocates within the community also attended the event, including Candis Cayne, Geena Rocero, Jen Richards, Laura Jane Grace and Chandi Moore.
Jenner wore a clingy black velvet dress and carried a sparkling clutch. She paired the ensemble with black open-toed heels.
Not only will we get to read about all the details of her glamorous birthday bash, we'll also get to watch it unfold when Season 2 of I Am Cait airs.
According to People, Jenner gave a brief speech, commending Rocero, who is a host and producer for the Beautiful As I Want to Be web series. Jenner also praised her work in the transgender community.
Jenner was honored during the launch event with a round of "Happy Birthday" and a cake, which was brought out to her by her friends at the event.
Cayne commented on Jenner's transition and the significance of her friend's "first" birthday.
"She is doing it really well," Cayne said, "and she's saying the right things, and starting to walk the walk, and talk the talk."
Cayne also added that Jenner is a clear spokesperson for the community, even though she doesn't want to be.
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