Rolvsøy is an island and a former municipality in Østfold county, Norway.
It was created by a split from Tune on 1 January 1911. At that time Rolvsøy had a population of 2,381. On 1 January 1994 Rolvsøy was incorporated into the municipality of Fredrikstad, the neighboring municipality to the south. Prior to the merger Rolvsøy had a population of 5,947.
The Tune ship, a viking ship dating from ca. 900 and now exhibited in the Viking Ship Museum in Bygdøy, Oslo was found in Rolvsøy in 1867. It was so named because it was found in a boat burial mound on Rolvsøy which was a part of Tune at that time.