Ruukki is a former municipality of Finland, located in the North Ostrobothnia region in the northern part of the country. It existed as an independent municipality until it was consolidated into a neighbouring city as part of Finland's nationwide municipal merger programme in the early 21st century.
Like much of North Ostrobothnia, the area is characterised by flat, low-lying terrain, extensive forests, and a network of rivers and marshland typical of the Bothnian coastal hinterland. The region experiences long, cold winters with persistent snow cover and short, relatively mild summers.
Following the merger, Ruukki no longer functions as a separate administrative unit and is today a district within its host municipality. Its history as an independent rural commune reflects the broader pattern of municipal amalgamation across Finland, which has reduced the number of municipalities substantially since the late 20th century.