Collin Gosselin thanks dad and sister Hannah in celebratory graduation post

Collin Gosselin is officially a high school graduate!

The former child TV personality, who starred with his parents and siblings in "Jon & Kate Plus 8," shared an Instagram post marking the milestone.

"Better late than never! Graduation ✅," the 19-year-old wrote in a post featuring photos of himself in a red graduation cap and gown.

"I wasn’t totally sold on the idea of making a graduation post, as most students graduate, therefore making it not such a big deal. So I decided to anchor this post more towards gratitude for mentors, friends, and of course family," Gosselin continued.

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Gosselin, a sextuplet and brother to twins, thanked his sister Hannah and father Jon, who appear in the first photo Gosselin included in his post, for their support through the years. The graduate also shared his gratitude for his father's ex-girlfriend, who he said supported him "day in and day out."

"I want to first thank my amazing sister, Hannah, for standing by me and supporting me, she is my number 1🤍 I would like to thank my dad, who has taught me so much about running into hard times and moving past them, about resilience. Thank you dad for always supporting my decisions, and having my back when I bite off more than I can chew. I’d like to thank Colleen for rooting for me day in and day out. When you think of someone you want by your side, you think of Colleen. And as I’ve told her many times, she is my motivator for being successful in this world," he wrote.

Gosselin went on to share his appreciation to his Army Junior ROTC leaders who he said taught him "the most valuable lessons" and revealed he will be heading to the Marine Corps training base in Parris Island, South Carolina, next, with plans to eventually study mechanical and industrial engineering in college.

Last November, Gosselin sat down for an exclusive interview with "Entertainment Tonight" and opened up about his personal and family life. The then-18-year-old said after his parents' divorce in 2009, he lived in two different institutions, one of which he was placed in by his mom Kate. Afterward, Gosselin said he moved in with his father and sister Hannah.

Gosselin said his past experiences led to an estrangement between him and his mother and his six other siblings, but he said he hoped they could reconnect in the future.