In addition to its status as a military fortress and home for Swedish nobility, the castle has seen use as a prison, and is currently a museum operated by the Finnish National Board of Antiquities.

The castle is one of the main tourist attractions of southern Finland, being the centerpiece of the city and a popular venue for events, including Renaissance fairs.

[citation needed] An earlier fortification from the early 1300s only some 20 kilometres (12 mi) away in Hakoinen also contests Tavastia Castle's age,[citation needed] as only one castle ("Tauestahus") is listed in Tavastia in a royal document from 1308.

Some restoration was conducted in the early 1600s, and in 1639, the castle's nearby settlements gained official city status as Hämeenlinna.

The castle continued to be neglected by Swedish rule throughout the 17th and 18th centuries, as its military interests shifted to the southern Baltic Sea.