Uusimaa (Finnish: Uudenmaa; Swedish: Nyland) is one of the 13 electoral districts of the Parliament of Finland, the national legislature of Finland. The district was established as Uusimaa Province (Finnish: Uudenmaan lääni; Swedish: Nylands län) in 1907 when the Diet of Finland was replaced by the Parliament of Finland. It was renamed Uusimaa in 1997. It is conterminous with the region of Uusimaa but excludes the municipality of Helsinki which has its own electoral district. The district currently elects 37 of the 200 members of the Parliament of Finland using the open party-list proportional representation electoral system. At the 2023 parliamentary election it had 801,205 registered electors.

Uusimaa Province was one 16 electoral districts established by the Election Act of the Grand Duchy of Finland (Suomen Suuriruhtinaanmaan Vaalilaki) passed by the Diet of Finland in 1906.^[4] It was conterminous with the province of Uusimaa.^[4] The municipalities of Anjala, Elimäki, Jaala and Kuusankoski were transferred from Uusimaa Province to Kymi Province in 1949.^[5] Helsinki city was separated into its own electoral district in 1952.^[6] The district was renamed Uusimaa in 1997.^[7][8] The municipalities of Artjärvi and Orimattila were transferred from Uusimaa to Häme in 1998.^[9]

Uusimaa currently elects 37 of the 200 members of the Parliament of Finland using the open party-list proportional representation electoral system.^[10][11] Parties may form electoral alliances with each other to pool their votes and increase their chances of winning seats.^[12][13] However, the number of candidates nominated by an electoral alliance may not exceed the maximum number of candidates that a single party may nominate.^[14] Seats are allocated using the D'Hondt method.^[15][16]