Kari Diesen (née Heide-Steen; 24 June 1914 – 18 March 1987) was a Norwegian singer and revue actress.

She was sister of actor Harald Heide Steen, and aunt of actor Harald Heide-Steen Jr. She was sister of opera singer Randi Heide Steen and thus aunt of Randi's daughter actress Anne Marit Jacobsen.

[6] After a career as a young ballerina for Ernst Rolf, she was engaged by Victor Bernau to his revue in the spring of 1930, where she performed the song "Det er forbudt for barn under 16 år".

[1] Her record debut came in 1938 when she sang two duets with Jens Book-Jenssen, "Oh – Mama – 6/8" and "En bitteliten pike i et stort hotell".

Her comeback in a television show in 1980, celebrating Leif Juster, led to renewed popularity and the subsequent recording of the album Det hender så mangt–, and she received the Spellemannprisen Honorary Award.