Washington-on-the-Brazos is an unincorporated community along the Brazos River in Washington County, Texas, United States.

Because of its location on the Brazos River and near major roads, Washington became a commercial center, drawing in new inhabitants from nearby areas.

After the outbreak of the Texas Revolution, General Sam Houston made his headquarters at Washington in December 1835.

The delegates worked until March 17, when they had to flee with the residents of Washington, to escape the advancing Mexican Army.

Although the county seat moved to Brenham in 1844, the town continued to thrive as a center for the cotton trade until the mid-1850s, as it was located on the Brazos River to use for shipping out the crop.

In 1841, local Masonic Lodge created its own school, and the Washington Female Academy briefly existed from 1856 to 1857.