"I've never seen him so animated," CNN's Max said of the meeting. "We had lots of time with him and he was on great form. I'm thrilled with the interview."
The interview is part of an hour-long special titled Prince William's Passion: New Father, New Hope, which will air on CNN on Sunday 15 September.
The special focuses on William’s passion for Africa - the continent where he chose to propose to Kate in 2010 - and his dream to save the world's most endangered species. In it, the Prince shares his hope that his newborn son will one day experience the same Africa that he and Harry did as young boys.
The brand new dad also reflects on the weeks since he became a parent and how fatherhood has changed him.
News of the interview follows William's first public appearance since the birth on his son. This week, having returned to duty as an RAF search and rescue pilot after two weeks paternity leave, he attended the Anglesey Show.
The first-time father was all smiles as he walked around the grounds and chatted to show-goers. Asked about his little son, William joked that George was "pretty loud and extremely good looking", adding that there had been "just a few sleepless night but (George) is sleeping much better now."
Given the excitement surrounding the arrival of the baby prince, Prince William's Passion: New Father, New Hope promises to give a revealing insight into William and Kate's first few weeks as parents. A portion of the interview will air on Monday 19 August.