And while they have always been open about their challenging journey to parenthood they had, until now, kept the identity of their surrogate under wraps.
But in a clip from the new season of their reality show Giuliana & Bill, the couple reveal the face of the woman who has brought them so much joy by carrying their baby son, Edward Duke.
The Us video shows the expectant parents touring the birthing room with Delphine, as they try to figure out a birthing plan for the big day.
In the end the delivery went without a hitch after a four-hour labor and Giuliana was the first to hold her baby boy while Bill cut the umbilical cord.
Bill has previously said that they "hit the gestational carrier lottery" being matched with the pretty brunette that gave birth to their son.
"She's giving us a gift and we're going to be eternally grateful," he said.
The new season of Giuliana & Bill premieres on Style on October 2.