"I can't believe my baby boy is now a teenager," John wrote, alongside a montage of photos and videos of the boy, set to Stevie Wonder's "You Are the Sunshine of My Life. "Ben turns 13 today. I love you my son!"
John and Kelly's daughter Ella Bleu Travolta, 23, also posted a tribute to her little brother on her own Instagram page. "Happy Birthday my sweetest Benjamin," she wrote alongside a childhood pic of the now-teen, "it feels like yesterday you were this young and now you're 13!! I love you!"
In addition to Benjamin, John and Kelly also raised son Jett Travolta, who died in 2009 at age 16 after suffering a seizure during a family vacation. His mom passed away in 2020 at age 57 following a two-year breast cancer battle.
John and Ella have occasionally paid tribute to their late loved ones on social media.
In October, the actors' daughter shared a childhood pic of herself with her mom on Kelly's birthday. "Happy Birthday mama, I love you so much!" Ella wrote on her Instagram page. "Thank you for inspiring me every day."
In addition, John and Ella have also often shared heartwarming glimpses of their own lives at home with Benjamin in recent years.
Look back at several of the Travoltas' family photos: