The BBC sci-fi drama, which first aired in November 1963, will mark its 50th year in 2013.
"I think it will be one of the biggest events that we've ever done - I think it has to be," Smith told Digital Spy.
Doctor Who showrunner Steven Moffat also promised that the anniversary celebrations would be "huge", but added that fans will have plenty to look forward to before 2013.
"We've got an awful lot of stuff to announce before that," he said. "We don't aim to have one event, over a year in the future - we want to make Doctor Who an event every single week. And we're going to pull that off, so... patience!"
"I just read the first draft of the script this morning and it's such a beautiful character piece," said Who exec producer Caroline Skinner. "It's something that Mark Gatiss has been wanting to write for the best part of a decade and it's a fabulous story.
"There are so many things that the fans will love about the origins of Doctor Who, but also the characters who made it are just such extraordinary people. It's something that will be a joy to bring to life."
Doctor Who will return to BBC One and BBC America on Saturday, September 1.