Kungälv is a city and the seat of Kungälv Municipality in Västra Götaland County, Sweden. It had 22,768 inhabitants in 2010.

According to Swedish official sources the city was founded in 1612, when the former settlement at Kungahälla was moved to the Bohus Fortress. However, this is disputed due to the fact that other sources indicate that it was the capital of Norway at one point under Sigurd I Magnusson.

Sigurd I Magnusson (Sigurd Jorsalfare/Sigurd the Crusader) was the King of Norway (1103–1130) and is the most well known crusader king of Scandinavia. He was also the first European king to join the crusades at a time where Kungälv was Norwegian territory.

Sigurd returned to Norway in 1111 where he made his capital in Konghelle (Kungälv in present-day Sweden) and built a castle there, where he kept a relic given to him by King Baldwin, a splinter reputed to be from the True Cross. Sigurd died in 1130 and was buried in Hallvardskirken (Hallvards church) in Oslo.

Sigurd I Magnusson marks the first verifiable royal presence in Kungälv which might indicate that the name originated from this era.