[3][7] Some of Kilgas' more memorable roles have been in stage productions of works by such composers and lyricists as: Emmerich Kálmán, John Kander, Paul Abraham, Jerry Herman, Franz Lehár, Eduard Tubin, Cole Porter, Johann Strauss, Jule Styne, Arthur Sullivan, Franz Schubert, and Heinrich Berté.

[8] Kilgas' first major film role was as Father in the 1989 Peeter Simm directed historical drama film Inimene, keda polnud, which chronicles the life of a young Estonian singer and actress named Imbi (played by Katri Horma) from the 1930s until the March 1949 deportations of Estonian citizens to inhospitable areas of the USSR by Soviet authorities.

[9] In 1991, he appeared as Kuno in the Eino Baskin directed Tallinnfilm drama Rahu tänav, starring Mikk Mikiver and Jüri Järvet.

The following year, he appeared as Leo in the Mati Põldre directed biographical period drama Need vanad armastuskirjad for Freya Film about the life of Estonian musician and lyricist Raimond Valgre (played by Rain Simmul) during the 1930s and 1940s and following the banning of his works in 1948 by Soviet authorities.

[10] In 2007, Kilgas returned to the screen to play the spirit of legendary Estonian singer and actor Georg Ots in the Andres Maimik and Rain Tolk directed Kuukulgur Film road movie comedy Jan Uuspõld läheb Tartusse; a film that portrays Estonian actor and singer Jan Uuspõld as a down-on-his-luck caricature of himself trying to hitchhike from Tallinn to Tartu to perform in a role at the Vanemuine theatre.

[11] Tõnu Kilgas has also worked as a voice actor, most notably dubbing foreign animated films into the Estonian language.

[16] For many Estonians, Kilgas is possibly best known for his role of Harry Ahven on the popular, long-running Eesti Televisioon (ETV) drama serial Õnne 13.