"I just love coming home," the Private Practice star, 38, told Usmagazine.com Monday at the American Cancer Society's "Blow Out Cancer" event in Beverly Hills. "I said before - it's like a great prize waiting at home."
Walker — the first child for Diggs and wife of six years, Idina Menzel — "is a joy that can’t be explained," the actor told Us.
"I love his smile," he added. "He’s always smiling."
In March, Usmagazine.com broke the news that the couple — who met on the 1996 Broadway production of Rent — were expecting.