Smith made a surprise visit to the theatre as they were adding the final touches for their 140-strong Olympic and Paralympic welcome ceremonies.
The actor said that the theatre "completely transformed my life. No understatement. I'm proud to be a part of it still. I care very deeply about it".
While the artistic director and chief operating officer for the theatre, Paul Roseby, who knew Matt when he attended the theatre said: "Matt is a perfect role model for the latest generation of brave new talent. Raw, fearless and a passion for theatre is something that doesn't just sum up our company but also the wonderful Matt Smith.
"As we continue to operate in challenging economic times, like everyone in the arts, it's always good to have a Doctor in the house."