- 23 Oct 17
The Chase host is one of a number of cast announcements which have been made for the sci-fi show today.
Mandip Gill and Tosin Cole have also joined the cast, which will feature Jodie Whittaker as the first female Time Lord.
Walsh, who has been a fan of the show for 50 years, is reported by Sky News to have been delighted at getting the role.
The actor and TV presenter had previously made a guest appearance as a villain in the Sarah Jane Adventures in 2008.
Walsh has previously starred in the likes of Coronation Street and Law & Order: UK, but is perhaps most popular for hosting The Chase gameshow.
Whittaker, who takes over from Peter Capaldi, will be the 13th Time Lord, and Walsh had been tipped to be the sidekick to the show's first female lead.
The BBC confirmed the series will have a 10-week run in autumn 2018.
— Doctor Who Official (@bbcdoctorwho) October 22, 2017