"HAPPY 19th BIRTHDAY to all my Kids!!" he captioned a throwback photo of the children. "I love you all so much!!"
Jon echoed this message in an Instagram Stories post, adding eight heart emojis for each of the kids.
Viewers watched Cara, Mady, Hannah, Leah, Alexis, Joel, Aaden and Collin grow up on the show Jon & Kate Plus 8, which premiered in 2007 and later evolved into Kate Plus 8 following Jon and Kate's 2009 divorce (the last episode aired in 2017). Over the years, fans have continued to follow their lives on social media, seeing them mark birthdays and first days of school.
However, the family dynamic is not what it once was. Hannah and Collin moved in with Jon while their siblings stayed with Kate. And while the DJ hasn't spoken to his six other children in years, he's hopeful this can one day change.
"My door has always been open to them," he told The Sun last month, "and I hope now they are adults they may want to reach out."