In a post on his Twitter.com page early on Thursday, Bill writes, "The 'Duke' has landed! Edward Duke Rancic was welcomed into the world last night at 7lbs 4oz. G & I feel blessed beyond words ... We did it!"
The couple turned to surrogacy after Rancic's fertility issues meant she struggled to go full-term with a pregnancy, and she miscarried a child in 2010.
"Technically this baby saved her life because had she not gone through IVF -- the doctor made it mandatory that she get a mammogram -- they would have never found what they found," he told Us. "So we owe this little guy debt of gratitude ..."
Keep clicking to see more photos of the proud new parents throughout their years together.