The core of the museum collection is formed by the works evacuated from the Vyborg art museum in 1939 due to the Second World War. After the war, part of these works was deposited in the Hämeenlinna Art Museum founded in 1952.

Over the span of five decades the museum collection has grown from a few hundred up to more than 8000 works due to the numerous donations and purchases.

The museum collection includes Finnish painting, sculpture, drawing and prints from the end of the 19th century up to the present day. There are also art textiles and photos as well as a small collection of international art.

Some of the most important works belong to the Golden Age of Finnish art: Larin Paraske by Albert Edelfelt, The Departure of Väinämöinen by Akseli Gallen-Kallela, The Savo Boat and A Day in July by Eero Järnefelt, Evening in the Forest by Berndt Lindholm, Eckerö Post Quay by Victor Westerholm and A Day in March by Pekka Halonen.