Justin Timberlake tries to keep his family life private, but he couldn't help himself when it came to celebrating his first Father's Day as a dad.

The "Take Back the Night" crooner posted a photo of himself holding his son, Silas, who's wearing a baby blue pj set with "I Love Dad" on his bottom. The moment looks even sweeter with the baby boy's head resting nicely on the curve of his father's neck.

"FLEXIN' on Fathers Day...#HappyFathersDay to ALL of the Dads out there from the newest member of the Daddy Fraternity!! --JT," Justin captioned a photo he posted to Instagram earlier this morning.

Justin and his wife, actress Jessica Biel, welcomed their baby boy in April. Naming him Silas Randall Timberlake, the couple was excited to become first-time parents.

While this photo doesn't show Silas' face, Justin posted the first-ever photo of Silas soon after his birth on Instagram. Carried by a smiling Jessica, Justin captures the baby in mid-yawn, which makes Silas look like he's winking at the camera. Clearly he'll be heartbreaker when he grows up.

We wish Justin a great Father's Day with his family!

See These Celeb Dads With Their Kids