Jett died in 2009 following an accident while the family was vacationing in the Bahamas. He was 16.
On Monday, Travolta posted a black-and-white photo showing him and Jett sharing a loving embrace. “Happy Birthday Jetty! We love you! ❤️,” he captioned the close-up pic.
Preston also shared a photo showing the pair enjoying a cuddle while bundled up in cozy clothing. “Happy Birthday to our sweetest Jetty, we love you!! 💖✨,” she wrote alongside the heartwarming snap.
The couple's daughter, Ella, meanwhile shared an old family portrait of the clan all glammed up together. “Happy Birthday to my brother Jett, I love you so much ❤️❤️❤️,” the 20-year-old wrote.
The occasion came days after Ella celebrated her birthday, while tackling her candles in a unique way.
Wearing a mask which prohibited her from blowing the flames out, she instead waved what appeared to be towels over the cake until the gush of air put them out.
“Found a safe way to put out birthday candles! Happy birthday Ella!” Travolta captioned a video of the hilarious moment.
The family has since enjoyed Easter weekend together, with Travolta -- who also has a 9-year-old son, Benjamin, with Preston -- sharing clips from their fun time on Instagram.
See more on the family below.