The singer and wife Jessica Biel secretly welcomed the tot last summer.
The singer even dressed like Phoebe Buffay for the occasion.
Chrissy Teigen Said She's 'Full of Regret' for Not Looking at Son Jack's Face When He Was Born
"I was so scared of seeing him in my nightmares that I forgot about seeing him in my dreams."
The Duchess of Sussex asked her husband to announce the news because "it sounds really nice with your accent."
The Duchess of Sussex is making royal history once again.
Teigen is currently on "super serious" bed rest.