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.

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.

[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.

Results of the 1954 parliamentary election held on 7 and 8 March 1954:[102][103][104][105][106] The following candidates were elected:[107] Saara Forsius (Kok); Veikko Helle (SDP); Gunnar Henriksson (SDP); Sven Högström (SFP); Hertta Kuusinen (SKDL); J. E. Lampinen (ML); Bertel Lindh (SFP); Juho Niukkanen (ML); Kurt Nordfors (SFP); Gösta Rosenberg (SKDL); Eino Saari (SK); Martta Salmela-Järvinen (SDP); Bruno Sundman (SDP); Unto Suominen (SDP); and Rainer Virtanen (SKDL).

Results of the 1951 parliamentary election held on 1 and 2 July 1951:[108][109][110][111] The following candidates were elected:[112] Margit Borg-Sundman (Kok); Karl-August Fagerholm (SDP); Veikko Helle (SDP); Gunnar Henriksson (SDP); Lassi Hiekkala (SK); Emil Huunonen (SDP); Aune Innala (Kok); Konsti Järnefelt (SK); Esa Kaitila (SK); Sylvi-Kyllikki Kilpi (SKDL); Henrik Kullberg (SFP); Hertta Kuusinen (SKDL); J. E. Lampinen (ML); Jussi Lappi-Seppälä (Kok); Tyyne Leivo-Larsson (SDP); Väinö Leskinen (SDP); Nils Meinander (SFP); Juho Niukkanen (ML); Kurt Nordfors (SFP); Arne Öhman (SFP); Ebba Östenson (SFP); John Österholm (SFP); Ville Pessi (SKDL); Gösta Rosenberg (SKDL); Mauri Ryömä (SKDL); Martta Salmela-Järvinen (SDP); Arvo Salminen (Kok); Bruno Sundman (SDP); Unto Suominen (SDP); Väinö Tanner (SDP); Arno Tuurna (Kok); Ernst von Born (SFP); and Atos Wirtanen (SKDL).

Results of the 1948 parliamentary election held on 1 and 2 July 1948:[113][114][115] The following candidates were elected:[116] Gunnar Andersson (SDP); Margit Borg-Sundman (Kok); Karl-August Fagerholm (SDP); Gunnar Henriksson (SDP); Lassi Hiekkala (KE); Emil Huunonen (SDP); Heikki Hykkäälä (SDP); Erkki Härmä (SDP); Rakel Jalas (Kok); Kalle Kauppi (KE); Sylvi-Kyllikki Kilpi (SKDL); Usko Koski (Kok); Henrik Kullberg (SFP); Hertta Kuusinen (SKDL); J. E. Lampinen (ML); Jussi Lappi-Seppälä (Kok); Erkki Leikola (Kok); Tyyne Leivo-Larsson (SDP); Nils Meinander (SFP); Arne Öhman (SFP); Arvi Oksala (Kok); Ebba Östenson (SFP); John Österholm (SFP); Ville Pessi (SKDL); Gösta Rosenberg (SKDL); Mauri Ryömä (SKDL); Martta Salmela-Järvinen (SDP); J. O. Söderhjelm (SFP); Unto Varjonen (SDP); Ernst von Born (SFP); and Atos Wirtanen (SKDL).

Results of the 1945 parliamentary election held on 17 and 18 March 1945:[117][118][119] The following candidates were elected:[120] Gunnar Andersson (SDP); Karl-August Fagerholm (SDP); C. O. Frietsch (SFP); Lassi Hiekkala (KE); Kosti Kankainen (Kok); Kalle Kauppi (KE); Sylvi-Kyllikki Kilpi (SDP); Hertta Kuusinen (SKDL); J. E. Lampinen (ML); Jussi Lappi-Seppälä (Kok); Erkki Leikola (Kok); Väinö Leskinen (SDP); Nils Meinander (SFP); Ebba Östenson (SFP); John Österholm (SFP); Arvo Paasivuori (SDP); Eino Pekkala (SKDL); Ville Pessi (SKDL); Kaisu-Mirjami Rydberg (SKDL); Mauri Ryömä (SKDL); Martta Salmela-Järvinen (SDP); Arvo Salminen (Kok); Maximilian Sergelius (SV); Cay Sundström (SKDL); J. O. Söderhjelm (SFP); Konsta Talvio (SKDL); Tyyne Tuominen (SKDL); Aaro Uusitalo (SKDL); Teuvo Valanne (Kok); Ernst von Born (SFP); and Atos Wirtanen (SDP).

Results of the 1924 parliamentary election held on 1 and 2 April 1924:[150][151][152][153] The following candidates were elected:[154] Artturi Aalto (SDTP); Aleksander Allila (STPV)); Mikko Ampuja (SDTP); Ilmari Auer (KE); Ragnar Furuhjelm (SFP); Hedvig Gebhard (Kok); Artturi Hiidenheimo (Kok); Eirik Hornborg (SFP); Kyösti Järvinen (Kok); Edvard Jokela (STPV); Erkki Kaila (Kok); Manu Kontula (SDTP); Gustaf Lindberg (SFP); Uno Nurminen (STPV); John Österholm (SFP); Axel Palmgren (SFP); Hjalmar J. Procopé (SFP); Hannes Ryömä (SDTP); Georg Schauman (SFP); Hilda Seppälä (SDTP); Leander Sirola (SDTP); Juho Vennola (KE); Ernst von Born (SFP); Karl Wiik (SDTP); and Rolf Witting (SFP).

Results of the 1908 parliamentary election held on 1 and 2 July 1908:[195][196][197][198] The following candidates were elected:[199] Frans Ahlroos (SFP); Werner Aro (SDP); Leo Ehrnrooth (SFP); Eero Erkko (NP); Onni Hallsten (SP); Edvard Valpas Hänninen (SDP); Walter Heimbürger (SFP); Vera Hjelt (SFP); Georg W. Johansson (SDP); Hilda Käkikoski (SP); Otto Wille Kuusinen (SDP); Oskari Laine (SP); William Lundström (SDP); Oskari Lylykorpi (SDP); Valfrid Perttilä (SDP); Vilho Reima (SP); Gustaf Rosenqvist (SFP); Emil Schybergson (SFP); Miina Sillanpää (SDP); Aatto Sirén (SDP); Karl Söderholm (SFP); Hedvig Sohlberg (SFP); and Kristian von Alfthan (SFP).