Mariehamn (Finnish: Maarianhamina) is the capital of Åland, an autonomous territory under Finnish sovereignty. Mariehamn is the seat of the Government and Parliament of Åland, and 40% of the population of Åland live in the city. Like all of Åland, Mariehamn is unilingually Swedish-speaking and around 88% of the inhabitants speak it as their native language.

The town was named after Maria Alexandrovna, the Empress consort of Alexander II of Russia. Mariehamn was founded in 1861, around the village of Övernäs, in what was at the time part of the municipality of Jomala. The city has since expanded and incorporated more of Jomala territory. The city is located on a peninsula, and has two important harbours, one located on the western shore and one on the eastern shore. The Western Harbour is an important international harbour with daily traffic to Sweden and mainland Finland. A powerful incentive for Baltic ferries to stop at Mariehamn is that, with respect to indirect taxation, Åland is not part of the EU customs zone and so duty-free goods can be sold aboard. Mariehamn Airport is located in the neighbouring municipality of Jomala, some 3 kilometres (2 mi) north-west of Mariehamn city centre.