Jānis Kalniņš (3 November 1904 in Pärnu – 30 November 2000 in Fredericton) was a Latvian Canadian composer and conductor.
Jānis Kalniņš was the son of composer Alfrēds Kalniņš. He was a student first of Jāzeps Vītols at the Latvian Academy of Music, then with Erich Kleiber, Hermann Abendroth and Leo Blech. His two major operas were Hamlets (1936) and Uguni (1937). He was chief conductor of the Latvian National Opera 1933-1944.
Kalniņš emigrated to Canada in 1948, taking a position as an organist in Fredericton, where he worked until retirement in 1991. He was awarded the Order of Vasa by the King of Sweden and the Order of the Three Stars by the State of Latvia, and received a New Brunswick Award for Excellence in the Arts in 1984, among others. Kalnins died in Fredericton in 2000.