The reality star also shared a video of her singing "Happy Birthday" to herself.
Kylie Jenner posed for her first Instagram pic as a 19-year-old.
Seated on a white couch, the reality star sported a Baywatch-inspired swimsuit on Wednesday, that perfectly matched her new red hair.
Kylie also posted a fun video of her singing "Happy Birthday" to herself.
A few weeks ago, the youngest Jenner sister admitted that turning a year older was bittersweet for her, but now that August 10 is finally here, she's in better spirits.
"I can't believe I'm 19!!! When I look back at the past year and all that has happened, it's seriously crazy," she wrote on her website. "I can't even imagine what this next year will bring -- not only for me, but for my friends and family, too!"
Kylie also shared her goals for the coming year, revealing that she wants to add "foundations, concealers, blushes and bronzers" to her cosmetics line, visit Egypt and get a game room in her house. One wish she had for sister Kendall Jenner was that she land the cover of American Vogue magazine.
WATCH: Kylie Jenner Rocks Sheer Catsuit While at Early 19th Birthday Celebration
Meanwhile, her famous family has been busy sending her well wishes.
Kendall was super excited to celebrate her sister. "Happy birthday, Kylie! I hope you have the best day!!! Even though we're so different, I love our special bond," the 20-year-old model shared on her website. "You'll always be my baby sister. Enjoy your last year of being a teenager!"
MORE: Tyga Surprises Kylie Jenner With a $200,000 Black Maybach for Her Birthday
Khloe Kardashian was the first of Kylie's sisters to post a birthday message, which included a video of the siblings goofing off. "My baby girl is about to be a year older ??? if anybody knows me, they know my obsession for my little sisters Is real," the 32-year-old Instagrammed. "I don't want you to get older! Why am I getting so sad? It's almost birthday time @kyliejenner."
Kim Kardashian West also called out her special connection with Kylie. "Even though you are the youngest among us, I am constantly amazed by your maturity. I am always learning from you and inspired by your dedication to your business. You are so true to yourself and I love that!" she wrote on her website. "You have always known exactly what you wanted and gone for it, and I love seeing your dreams come true. I found all these old pics of us just hanging out, so happy we have all these memories to share."
Kim went on to note how well Libras, her zodiac sign, get along with Leos, Kylie's sign. "Libra and Leo share a really active relationship, full of bright conversation and adventures. Sometimes we end up spending too freely because we like doing stuff together a lot, LOL!" she added. "A friendship between a Leo and Libra is one of mutual assistance and collaboration. We're two signs apart in the zodiac, which means we communicate really well with each other."
Kylie's mother, Kris Jenner, also got sentimental about her youngest daughter turning 19. "I can't believe my baby girl is 19 today!!!! @kyliejenner I've watched you grow into the most loving, kind-hearted, funny, motivated, beautiful young woman and I couldn't be prouder of you!!" the 60-year-old momager wrote. "There are so many amazing adventures ahead for you, my sweet girl, this is just the beginning!!! I can't wait to see what life has in store for you. I wish you the most amazing day today. You are my heart, a true blessing and I love you beyond words!!!!! #birthdaygirl #love #proudmama #blessed #happybirthdaykylie"
Here's a look at all Kylie accomplished before 19:
