The Communist Party of West Belarus (Belarusian: Камуністычная партыя Заходняй Беларусі, КПЗБ, KPZB) was a banned Belarusian political party in Poland-controlled West Belarus from 1923 until 1939.
The party was founded in 1923 in Wilno by representatives of Belarusian communist circles from Wilno, Białystok and Brest. In 1924 a youth branch of the party was created.
The party's political program included a socialist revolution in Poland, independence of West Belarus with a subsequent unification with the Belarusian Soviet Socialist Republic. The party worked undercover, in 1925-1927 partly masked by the activities of the legal Belarusian Peasants' and Workers' Union. It received support from the Soviet Union and was actively involved in the anti-Polish resistance.
In 1938, following a decision by the Comintern, the KPZB along with the Communist Party of Poland and the Communist Party of Western Ukraine was dissolved.
After the annexation of Western Belarus to the Soviet Union in 1939 many former members of the KPZB were repressed, others joined the Communist Party of Byelorussia, the East Belarusian branch of the Communist Party of the Soviet Union.