The district was established as Oulu Province South (Finnish: Oulun läänin eteläinen vaalipiiri; Swedish: Uleåborgs läns södra valkrets)[4] in 1907 when the Diet of Finland was replaced by the Parliament of Finland.

The district currently elects 18 of the 200 members of the Parliament of Finland using the open party-list proportional representation electoral system.

Oulu Province South 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.

[7][8] Oulu currently elects 18 of the 200 members of the Parliament of Finland using the open party-list proportional representation electoral system.

[9][10] Parties may form electoral alliances with each other to pool their votes and increase their chances of winning seats.

Results of the 1917 parliamentary election held on 1 and 2 October 1917:[165][166][167][168] The following candidates were elected:[169] Kustaa Ahmala (SDP); Kusti Arffman (ML); Santeri Haapanen (ML); Juho Heikkinen (ML); Matti Hoikka (SDP); Kyösti Kallio (ML); Kalle Korhonen (SDP); Arthur Lagerlöf (SP-NP-KP); Ivar Lantto (ML); Hugo Linna (SP-NP-KP); Yrjö Mäkelin (SDP); Kaarlo Juho Ståhlberg (SP-NP-KP); and Leonard Typpö (SP-NP-KP).

Results of the 1916 parliamentary election held on 1 and 3 July 1916:[170][171][172][173] The following candidates were elected:[174] Jalmari Haapanen (ML); Santeri Haapanen (ML); Kalle Hautala (SDP); Matti Hoikka (SDP); Kyösti Kallio (ML); Yrjö Komu (SDP); Kalle Korhonen (SDP); Ivar Lantto (ML); Yrjö Mäkelin (SDP); Filip Saalasti (ML); Aale Sariola (SP); Kaarlo Juho Ståhlberg (NP); and Leonard Typpö (SP).

Results of the 1913 parliamentary election held on 1 and 2 August 1913:[175][176][177][178] The following candidates were elected:[179] Heikki Ahmala (SDP); Kalle Jäykkä (ML); Kyösti Kallio (ML); Juho Komu (SDP); J.

A. Mannermaa (SP); Yrjö Mäkelin (SDP); Oskari Partanen (ML); Salomo Pulkkinen (ML); Filip Saalasti (ML); Kaarlo Juho Ståhlberg (NP); Heikki Törmä (SDP); Leonard Typpö (SP); and Iisakki Vahe (SP).

Results of the 1909 parliamentary election held on 1 and 3 May 1909:[190][191][192][193] The following candidates were elected:[194] Arthur Castrén (NP); Santeri Haapanen (SP); Juho Heikkinen (ML); Matti Hoikka (SDP); Kyösti Kallio (ML); Otto Karhi (ML); Juho Komu (SDP); Arthur Lagerlöf (SP); Artturi Laitinen (ML); Antero Leinola (ML); Yrjö Mäkelin (SDP); Kalle Myllylä (SP); and Heikki Törmä (SDP).

Results of the 1908 parliamentary election held on 1 and 2 July 1908:[195][196][197][198] The following candidates were elected:[199] Anna Ängeslevä (ML); Juho Heikkinen (ML); Matti Hoikka (SDP); Kyösti Kallio (ML); Juho Komu (SDP); Arthur Lagerlöf (SP); Ivar Lantto (ML); Yrjö Mäkelin (SDP); Kalle Myllylä (SP); Jaakko Piirainen (SDP); Mauno Rosendal (NP); Antti Tuomikoski (SP); and Iisakki Vahe (SP).

Results of the 1907 parliamentary election held on 15 and 16 March 1907:[197][200][201][202] The following candidates were elected:[203] Juho Heikkinen (ML); Matti Hoikka (SDP); Kalle Hämäläinen (SDP); Kyösti Kallio (ML); Otto Karhi (ML); Heikki Kiiskinen (ML); Mikko Knuutila (NP); Juho Komu (SDP); Arthur Lagerlöf (SP); Albert Luoma (NP); Kalle Myllylä (SP); Aate Olkkonen (SP); and Iisakki Vahe (SP).