Having taken part in the show's 2015 Christmas special alongside Peter Capaldi and Alex Kingston, Lucas will reprise the role of River Song's former assistant Nardole.
"I'm chuffed to bits that Nardole is returning to the Tardis for some more adventures," Lucas said.
The star will appear in the opening episode of series 10, which begins filming in Cardiff on 20 June.
Steven Moffat, lead writer and executive producer, added he was "delighted and slightly amazed to be welcoming Matt Lucas back on to the Tardis - and this time it's not just for Christmas, he's sticking around".
"One of the greatest comedy talents on planet Earth is being unleashed on all of time and space."
Capaldi will return as The Doctor while Pearl Mackie replaces Jenna Coleman as his new companion, Bill, in her first major television role.
Lucas said he was looking forward to reprising his role in the sci-fi drama because he "loved acting with Peter and I'm excited to work with Pearl".
Also announced to be joining the series this year is Jekyll & Hyde and Sherlock star Stephanie Hyam.
Doctor Who will return to BBC One with a December Christmas special followed by a new series in 2017.
Matt Lucas is set to return to Doctor Who for its 10th series.