The former footballer told ITV's Lorraine that he was thrilled to hear close friend The Duke of Cambridge and his wife were expecting a second child.
David and his wife Victoria were guests at William and Kate's wedding back in 2011. David and William have been friends since working together on England's World Cup bid. David also recently joined William's #WhoseSideAreYouOn wildlife conservation campaign.
"I'm so happy for them both because they're such great parents and obviously to be great parents and to have the roles that they have, as important as they have, is really incredible," he said.
"I'm just happy they're going to have another little one running around the house!"
David and Victoria are parents to four children themselves - Brooklyn, 15, Romeo, 12, Cruz, 9, and three-year-old Harper - so did David have any advice on handling two kids?
"Get some sleep because jumping from one child to two is a big step!" he laughed. "Even though I thought jumping from two to three was bigger."
Prince William, 32, and Kate, also, 32, welcomed their first child together, Prince George, in July 2013.
News of the second pregnancy was announced by Clarence House this week, with a representative saying the royal couple and their families were thrilled by the impending arrival.
Unfortunately for Kate, she is once again suffering from hypemesis gravidarum, a very extreme form of morning sickness. During the early stages of her pregnancy with Prince George she was hospitalised for three days. This time around, she is being treated by doctors at Kensington Palace.
Kate's condition meant she was forced to pull out of a planned engagement in Oxford with Prince William this week. William attended solo and told reporters the last week had been "tricky" for his poorly wife and he was hoping things would settle down soon.
The duchess has also cancelled an appearance at tonight's Invictus Games Opening Ceremony in London, while aides have suggested her planned visit to Malta on 21 September - her first overseas solo tour - could also be postponed.
Stars congratulate William and Kate:
Reveal is now on Google Plus! Join us here for the latest pictures, fashion and celebrity news!