Maarten de Niet Gerritzoon (16 March 1904 – 25 July 1979) was a Dutch politician.
During the Second World War, he was a prisoner in several Japanese prisoner-of-war camps, like Sukamiskin Penitentiary in Bandung.
After the war he became a member of the PvdA and was considered to be very progressive. Between 1950 and 1969 he was mayor of Wageningen. From 1956, he was a member of the Senate as well. As a senator, he often collided with Minister of Foreign Affairs Joseph Luns on the issue of Netherlands New Guinea. In 1969, he replaced Jannes Pieter Mazure as president of the Senate. In 1973 De Niet was succeeded by Theo Thurlings.