Several hundred people came to pay their last respects, including family and friends, as well as local residents who hear Knapik's distinctive voice daily on Warsaw's public transport system, Polish Radio's IAR news agency reported.
A longtime collaborator with both Polish Radio and state broadcaster TVP, he read the Polish-language versions of hit movies and drama series such as Twelve Angry Men, X-Files and Star Wars.
Knapik also worked for the Polish newsreel production company, and his voice graced films, TV programmes, commercials as well as Warsaw's trams and buses.
Born in 1943 in Warsaw, he pursued an education that eventually saw him earn a Ph.D. in automotive engineering and become a lecturer at the Warsaw University of Technology.
At the same time, even before finishing high school, Knapik embarked on a media career that included stints at Polish Radio and TVP.
After 1989, he became the voice of the Polish newsreel until the programme's end, then established cooperation with the sound studios which created voiceovers for movies and drama series aired by private TV networks.
One of Poland's most recognisable voices for many years, Knapik would have turned 78 on September 16. He died last Monday.