The history of the museum in Siedlce dates back to 1928 when, thanks to the City Council’s resolution, the Museum of the Podlasie Region was created.
It was located in the XVIII century town hall at the top of which is the figure of Atlas called by Siedlce inhabitants "Jack". The museum had different sections. There were various objects gathered from the field of archaeology, history, ethnography and art. The collections were destroyed in July 1944 when the town hall was on fire.

After World War II in 1967 the museum was reactivated with its seat placed in the town hall. It functioned under different names: the Museum of the Podlasie Region until 1975, the District Museum in the years 1975-1999 which is now called the Siedlce Regional Museum.

In the museum there are gathered, prepared and displayed various cultural goods from the field of art, history, ethnography and archaeology. There are researches led and educational activities, displays and publishings. In the museum structure there are two branches: the Museum of Armed Struggle and Martyrology in Treblinka and the Kotuń Firefighting Museum.