Stewart participated in the birth of his 7-pound, 7-ounce son early Sunday morning at St. John and St. Elizabeth Hospital, Stewart's label, J Records said in a news release Monday.
"Both Penny and our baby son are gorgeous, healthy and doing well," Stewart said. "I am so very proud of my girl Pen for the commitment, courage and strength she showed throughout."
The couple are now home with their son in Epping, England.
"We are celebrating every moment with our beautiful boy," he said. "We just can't take our eyes off him."