The baby, Louis Augustus Walton, was born Nov. 10 at Cedars-Sinai Hospital in Los Angeles, Walton told People magazine.
Walton said he and Delfino were caught off-guard at their son's early arrival, which included an "action-packed trip back to Los Angeles" from Ojai, Calif., where they were at the time Delfino went into labor.
The trip included a "close call on the side of the road" he said.
"Louis is as healthy as can be," Walton told People.
Louis joins 17-month-old sister Cecilia Delphine Walton.