The Treaty of Bassein was a pact between the British East India Company and Baji Rao II, the peshwa of the Maratha Confederacy. It was signed on 31 December 1802 after the Battle of Poona, in present-day Bassein (Vasai). The treaty was a decisive step in the dissolution of the Maratha Empire, which led to the East India Company's annexation of the empire's territories in western India in 1818.