Speaking today (December 2) at a BAFTA session, Moore promised that the Thick of It star is "going to be a really fantastic Doctor".
"He's an extraordinary actor with amazing ability and just watching the first scenes come through… I'm very excited," she said.
Doctor Who showrunner Steven Moffat previously addressed rumours that the new Doctor could be female, arguing that gender should not dictate who plays the show's main role.
"It was about finding the right person, rather than what gender they might be," Moore agreed.
"We didn't go in with any agenda, but when you know you've found the right Doctor, you all stick on the right Doctor. I'm delighted that Peter said yes."
Doctor Who will return to BBC One this Christmas, with Capaldi starring in his first full series in late 2014.
Doctor Who Moffat on Capaldi: "It's time for the old beast to snarl"
Watch Peter Capaldi's unveiling as the new star of Doctor Who below: