The Treaty of Fredrikshamn, or the Treaty of Hamina, was a peace treaty concluded between Sweden and Imperial Russia on 17 September 1809. The treaty concluded the Finnish War and was signed in the Finnish town of Hamina. Russia was represented by Nikolay Rumyantsev and David Alopaeus, while Sweden by Infantry General Kurt von Stedingk and Colonel Anders Fredrik Skjöldebrand.

The history of Sweden from 1772 to 1809 is better known as the Gustavian era of Kings Gustav III and Gustav IV, as well as the reign of King Charles XIII of Sweden.