Sigurd Jonsson (1390s – December 1452) was a Norwegian nobleman, knight and the regent of Norway during two interregnums in the mid-15th century.

At the time of Sigurd's birth, Jon Marteinsson was a resident in Norway and a member of the Norwegian Council of the Realm (riksrådet).

[2] In 1436, a peasant rebellion led by Amund Sigurdsson Bolt rebelled against King Erik and his officials, besieging Oslo and Akershus Castle.

[5] In 1440, the Norwegian Council of the Realm was compelled to follow the example of Sweden and Denmark, and depose King Eric.

Norway followed Denmark and Sweden in electing Christopher of Bavaria as the new king, thus maintaining the union between the three countries.

He was the commander of Akershus Fortress from 1440 to 1445, and one of the leading proponents of the anti-Hanseatic policies in Norway during King Christopher's reign.

Sigurd was at the coronation of Christian in Trondheim and the signing of the Norwegian-Danish union treaty in Bergen in August 1450.

When Sigurd Jonsson died, his only son, Hans Sigurdsson inherited large estates, both in Norway and Shetland.