It consists of the municipalities of Aremark, Fredrikstad, Halden, Hvaler, Indre Østfold, Marker, Moss, Råde, Rakkestad, Sarpsborg, Skiptvet and Våler in the county of Viken.

The constituency currently elects eight of the 169 members of the Storting using the open party-list proportional representation electoral system.

Østfold currently elects eight of the 169 members of the Storting using the open[a] party-list proportional representation electoral system.

Results of the 2021 parliamentary election held on 13 September 2021:[13] The following candidates were elected:[14] Elise Bjørnebekk-Waagen (Ap); Kjerstin Wøyen Funderud (Sp); Stein Erik Lauvås (Ap); Ole André Myhrvold (Sp); Jon-Ivar Nygård (Ap); Freddy André Øvstegård (SV); Tage Pettersen (H); Ingjerd Schou (H); and Erlend Wiborg (FrP).

Results of the 2017 parliamentary election held on 11 September 2017:[15] The following candidates were elected:[16] Elise Bjørnebekk-Waagen (Ap); Svein Roald Hansen (Ap); Stein Erik Lauvås (Ap); Ulf Leirstein (FrP); Ole André Myhrvold (Sp); Freddy André Øvstegård (SV); Tage Pettersen (H); Ingjerd Schou (H); and Erlend Wiborg (FrP).

Results of the 2005 parliamentary election held on 11 and 12 September 2005:[21][22] The following candidates were elected:[23] Martin Engeset (H); Jon Jæger Gåsvatn (FrP); Vigdis Giltun (FrP); May Hansen (SV); Svein Roald Hansen (Ap); Line Henriette Holten Hjemdal (KrF); Irene Johansen (Ap); Ulf Leirstein (FrP); and Signe Øye (Ap).

Results of the 2001 parliamentary election held on 9 and 10 September 2001:[21][22] The following candidates were elected:[24] Martin Engeset (H); May Hansen (SV); Svein Roald Hansen (Ap); Øystein Hedstrøm (FrP); Odd Holten (KrF); Signe Øye (Ap); Henrik Rød (FrP); and Ingjerd Schou (H).

Results of the 1924 parliamentary election held on 21 October 1924:[96][97] The following candidates were elected:[96] Johannes Olaf Bergersen (S); Johan Kristian Hansen Ileby (H-FV); Gunder Anton Johannesen Jahren (H-FV); Peder Kolstad (Bp); Andreas Maastad (Bp); and Peter Olai Thorvik (S).

Results of the 1921 parliamentary election held on 24 October 1921:[98][99] The following candidates were elected:[98] Johannes Olaf Bergersen (S); Johan Kristian Hansen Ileby (H-FV); Gunder Anton Johannesen Jahren (H-FV); Peder Kolstad (L); Johan Fredrik Olsen Maseng (V); and Peter Olai Thorvik (S).