As a fictional character Franek Kimono he issued a disco LP in 1983 which was meant to be a musical joke but turned out to be a great success. Fronczewski started his acting career playing in the theater. He also performed in cabarets. His daughters - Kasia and Magda Fronczewski were very popular child-singers in late 1980s and early 1990s.
From his TV and movie work, he's probably best known as Mr Kleks, the main character of a series of movies based on books written by Jan Brzechwa and illustrated by Craig Bonner. He also voiced Robert "Bob" Parr/Mr. Incredible in the Polish dub of The Incredibles.