The Hobbit star said that he would return to his role as Doctor John Watson "the week after next".
When asked whether he had read the scripts, Freeman said: "Yes, it's brilliant."
However, the actor remained coy about what is in store for the characters after the huge cliffhanger at the end of series two's 'The Reichenbach Fall'.
Quizzed by Norton on whether he knew how Benedict Cumberbatch's Sherlock had survived at the end of the last series, he said: "Do you know what, no. Even we on reading the script aren't quite sure. Mark Gatiss is a clever fellow."
At last year's Edinburgh TV Festival, Sherlock creators Steven Moffat and Mark Gatiss revealed the teaser clues 'Rat', 'Wedding' and 'Bow' as hints for what Sherlock Holmes stories the third series will be based on.
The third series of Sherlock is expected to air on BBC One later this year.
Watch Martin Freeman discuss the new Sherlock with Digital Spy below: