General elections to the Icelandic parliament, Althingi, were held on 25 September 2021 under Act No 24 from May 2000. There are now six constituencies of which two are in Reykjavík. The total number of voters on the electoral roll was 254,586 or 69.0% of the total population.

Participation of voters in the general elections was 203,898 or 80.1% of the total number of voters on the electoral roll. Participation of female voters was slightly higher than that of male voters or 81.5% women compared with 78.7% men. The participation varied by age, it was lower among young voters than the older ones. Participation was 83.0% among persons with no foreign background, while it was 42.1% among immigrants.

During the elections, 47,696 voted with absentee votes or 23.4% of the electorate, while the comparable percentage was 18.6% in the 2017 elections.

General elections to the Althingi 25 September 2021 - Statistical Series