“Pigtails,” the proud papa, 36, captioned the sweet snapshot.
Mama Leah Jenner also Instagrammed a video bowling with their toddler.
Caitlyn Jenner – who welcomed Brandon with his ex-wife Linda Thompson – recently opened up about his oldest child supported her transition from the very beginning.
“I started with my son Brandon, because he’s like our little family Gandhi,” Caitlyn said. “He just has this great outlook on life and a very open mind. I figured he would be the easiest, so I sat down with him and his wife Leah and told them my whole story.”
Caitlyn added: “At the end, good old Brandon goes, ‘You know, Dad, I’ve always been really proud to be your son … and proud of everything you’ve done in your life. But I’ve never been more proud of you than I am right now.’ I cried. It was a really nice thing to say, and that really set the tone for (telling the rest of the family) and I started moving forward.”