Cardiff here we come!
He will be joined on Wednesday evening by actors Karen Gillan and Arthur Darvill, who play Amy Pond and her TV husband Rory.
Smith is filming his second series - much of which is shot in and around Cardiff - as the 11th incarnation of the Time Lord for BBC Wales.
The switch-on takes place on King Edward VII Avenue at 1940 GMT.
Smith said: "It's a real honour to be asked to switch on Cardiff's Christmas lights because the city has become like a second home to not only me, but the rest of the Doctor Who production team.
"We love filming here in Wales and we even managed to get into the festive spirit extra early this year when filming the Doctor Who Christmas special in August.
"Cardiff is a great city and I'd like to thank all of its residents for being so welcoming and accommodating."
The light switch-on also marks the 10th anniversary of Cardiff's 'Winter Wonderland' celebrations, which turn the city's civic centre into an open-air ice rink and fair.
Source: BBC
