Kourtney jetted off with sister Kim Kardashian West and friends Simon Huck and Jonathan Cheban to Iceland for a scenic celebration -- and the pics and videos -- from the waterfalls to her delicious birthday cake -- are incredible
"Happy Birthday @kourtneykardash," Kim, 35, captioned a flashback photo of herself and Kourtney on Tuesday. "Thank you for always doing everything first so I can copy you! I don't know what I would do without you! I love you! Happy Birthday!"
Meanwhile, back in the U.S., Kourtney's other family members were sharing sweet photos and videos of the birthday girl.
Kris Jenner was one of the first to wish her oldest daughter a happy birthday with a baby pic. "You have brought so much love, joy, and happiness into my life and I'm proud to be your mom," the 60-year-old momager Instagrammed. "You teach all of us everyday what it means to be an amazing daughter, mom, sister, friend, and a genuinely beautiful human being. Thank you for being such a bright light and an inspiration to me every day. You are kind and patient and have the biggest heart and I love you more than you will ever know. You will always be my firstborn who captured my heart.... Oh, and I'm really sorry about this outfit I put you in."
"Happy birthday @kourtneykardash!! What would our family do without you?!?!" sister Khloe, 31, posted along with another throwback photo. "This picture sums us up, even though I'm covered in chicken pox, you're still chillin by my side. I love you!!!"
Kylie Jenner took it to the next level and posted a video tribute on her website. "Wishing my big sister Kourtney the happiest birthday! Love you, Kourt," the 18-year-old reality star wrote.
Kendall Jenner also shared a message on her website, writing: "Happy Birthday Kourt!!! I love how well we get along since we're so similar. It's amazing to have a sister and role model like you in my life. I love you so much. You're the best!"
Last week, Kourtney proved that she hasn't aged in over a decade by sharing a throwback pic from her 20th birthday. Check out the flawless photo: