Kyminlinna is situated at the confluence of the eastern and western branches of the Kymijoki River. In 1791 the Russians built a small star-shaped field fortification at this military significant river crossing point. It became clear in the early 19th century that this location required a more robust defensive fort. In 1803 construction began on a modern caponier fortification to the designs of the Dutch-born General Peter van Suchtelen. Kyminlinna was founded to defend the fortified town and naval harbour of Ruotsinsalmi, together with which it formed the dual fortress of Ruotsinsalmi-Kyminlinna. Kyminlinna would dominate the whole of Hovinsaari Island, making it impossible to overrun Ruotsinsalmi by land. The fortress would also close off traffic on the main highway in southern Finland at the main crossing point of the Kymi Delta. It was also decided to make the fortress of sufficient strength and size to be able to withstand a prolonged siege without help from the outside and provide supporting fire for battles nearby. In its time, Kyminlinna was classified as a long-term fortress, later on referred to a magazine fortress.

1803-1917 A Russian garrison is stationed at Kyminlinna, and temporary wooden barracks are constructed for its purposes.

1922-1939 The Ministry of the Interior sets up a reception centre at Kyminlinna for refugees fleeing the Soviet Union.

1939 Kyminlinna taken over by the Finnish armed forces.

1982 Restoration of Kyminlinna begins.

Kyminlinna is transferred to civilian use in 2003-2004 and preparations are made to open it up for tourism and cultural uses.