Clarkson took to Twitter on Sunday to post the adorable photo of her husband, Brandon Blackstock, holding Remington and their 2-year-old daughter, River, in his arms.
"Happy Father's Day @BBlackstock," the 34-year-old "Piece by Piece" singer captioned the cute pic. "Thnx 4 being such a great dad 2 all 4 of our kiddos! #sexydaddyalert."
Blackstock also has two children, daughter Savanna and son Seth, from a previous marriage.
Clarkson has only shared a handful of photos of her newborn son since welcoming him in April, including this adorable black-and-white snapshot introducing Remington to the world when he was a week old.
Country legend Reba McEntire, ex-wife of Blackstock's father, Narvel Blackstock, spoke with ET back in May and marveled over meeting Remington when he was a day old, exclaiming, "We're buddies already!" Check out the video below to hear more from McEntire about meeting Clarkson's new bundle of joy.