Johann Gottlieb Janitsch (19 June 1708 – 1763) was a German Baroque composer.
Janitsch was born in Schweidnitz, Silesia. He graduated from the University of Frankfurt an der Oder. He held various positions at the court of the Kingdom of Prussia, eventually becoming the personal musician of Frederick the Great. Janitsch died in the Prussian capital Berlin. Unfortunately, much of his music was lost during World War II. His manuscripts were stored at the Sing-Akademie zu Berlin which was plundered during the war. Twenty-eight quadro sonatas have survived to modern times.