The actor, along with head writer Steven Moffat, made their mark by sinking their hands into cement to go on display at the exhibition.
Smith said: "I can't get my hands out! I'm here in stone now, so they can never forget."
Among the new exhibits for The Doctor Who Experience were the two two robots from Dinosaurs on a Spaceship - which were voiced by comedy duo David Mitchell and Robert Webb.
Speaking about new companion Jenna-Louise Coleman, Matt added: "Like with any companion and Doctor relationship, the chemistry and dynamic is something that is constantly evolving and hopefully constantly progressing as the story progresses.
"I very much enjoy working with Jenna, she's very detailed, she works very hard, she's very prepared, I think she looks great and I think she'll prove to be very popular."
The Doctor Who Experience is currently open in Cardiff. For more information, visit the official website.
(Source: BBC News)