Mariss Jansons (born 1943) is a prominent Latvian conductor.

Jansons was born in Riga, the son of conductor Arvid Jansons . His mother, who was Jewish, gave birth to him in hiding after her father and brother were killed in the Riga ghetto . In 1946, his father won second prize in a national competition and was chosen by Yevgeny Mravinsky to be his assistant at the Leningrad Philharmonic. When his family joined him in 1956, young Jansons entered the Leningrad Conservatory, where he studied piano and conducting, although his father urged him to continue playing violin. In 1969 he continued his training in Vienna and in Salzburg with Herbert von Karajan.

In 1973, Jansons was appointed Associate Conductor of the St. Petersburg Philharmonic Orchestra (formerly the Leningrad Philharmonic). In 1979, he was appointed music director of the Oslo Philharmonic Orchestra, with which he has performed, recorded and toured extensively. In 1992, Jansons was named principal guest conductor of the London Philharmonic Orchestra. In March 1997, he was appointed music director of the Pittsburgh Symphony Orchestra.

In 1996, Jansons nearly died on the Oslo podium, felled by a heart attack while conducting the final pages of La Bohème. Surgeons in Pittsburgh fitted a defibrillator in his chest to give his heart an electric jolt if it fails. (Jansons's father died on the podium.)

Starting in September 2004, Jansons is the sucessor to Riccardo Chailly as the chief conductor of Amsterdam's Concertgebouw Orchestra.