Justin Timberlake and son Silas on Father's Day 2015
Credit: Instagram/justintimberlake

It's official: Justin Timberlake is the latest member of the "Daddy Fraternity." He commemorated the special moment with an Instagram post featuring himself with his and wife Jessica Biel's new baby boy, Silas Randall Timberlake (above).

The beaming new dad wrote in the photo's caption, "FLEXIN' on Fathers Day ... #HappyFathersDay to ALL of the Dads out there from the newest member of the Daddy Fraternity!! --JT." Aww! We're not sure what's cuter: that sweet message or Silas's adorable "I heart Dad" onesie.

This is the first photo we have seen of baby Silas since Timberlake shared one of him right after his birth in April dressed in a tiny Memphis Grizzlies jersey while being cradled in his mother's arms.

Congratulations on your first Father's Day, Justin!