[1] The current flag of the Masovian Voivodeship is a red rectangle with the aspect ratio of height to width of 5:8.

On its left side is located silver (white) eagle with golden (yellow) beak and legs.

[2][3] In 1410, during the Battle of Grunwald, the forces of Siemowit IV, duke of the duchies of Płock, and Rawa, located in Masovia, used a red banner with a white eagle, with elevated wings, and its head turned left.

The flag was a red rectangle with the silver (white) eagle with golden (yellow) beak and legs, placed in the middle.

[5][6] The eagle has been taken from the coat of arms of the Masovian Voivodeship, which originally, was based on the seal used by Siemowit III, Duke of Masovia in 14th century.