Mikołajki () is a resort town in Mrągowo County, Warmian-Masurian Voivodeship in north-eastern Poland, with 3,338 inhabitants as of 2025. The town is located near the Śniardwy, the largest lake of both the Masurian Lake District and Poland. It is located in the center of the ethnocultural region of Masuria.

History

thumb|left|Preparing whitefish in the 1920s

Mikołajki is an old Masurian church town first documented as Nickelsdorf (Sankt Niklas) in 1444 and Niklasdorf in 1493. The name refers to Saint Nicholas (Mikołaj in Polish). Early on, it was part of the State of the Teutonic Order. In 1454 Polish King Casimir IV Jagiellon incorporated the region to the Kingdom of Poland upon the request of the anti-Teutonic Prussian Confederation, and the Thirteen Years' War broke out. After the war ended in 1466 it was part of Poland, as a fiefdom held by the Teutonic Knights and, from 1525 on, the Duchy of Prussia, founded as a vassal state of Poland. Similar to all of Masuria, it was mainly inhabited by Poles, hailing from nearby Masovia. In 1539 the inhabitants of the settlement were almost entirely Poles, who called it by its Polish name Mikołajki. First Protestant pastors were mentioned in 1552.

As a result of the treaty of Versailles the 1920 East Prussian plebiscite was organized on 11 July 1920 under the control of the League of Nations, which resulted in 1,800 votes to remain in Germany and none for Poland. During World War II it was one of the few Masurian towns not destroyed from the fighting, following the war it became again part of Poland under its historic Polish name Mikołajki.

Sports

Since 2005, the Rally of Poland has been based in Mikołajki.

The local football team is Kłobuk Mikołajki. It competes in the lower leagues.

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File:Mikołajki 02.jpg|The view of Mikołajki from Mikołajskie Lake (Jezioro Mikołajskie)

File:Mikolajki jezioro mikolajskie.jpg|The view of Mikołajskie Lake (Jezioro Mikołajskie)

File:POL Mikolajki 13.jpg|The view of Mikołajki from the marina.

File:Mikołajki, Poland - panoramio (3).jpg|Skyline of Mikołajki

File:POL Mikolajki 02.jpg|Lutheran Holy Trinity church