The Pawtuxet River, also known as the Pawtuxet River Main Stem and the Lower Pawtuxet, is a river in the U.S. state of Rhode Island. It flows 12.3 miles (19.8 km) and empties into the upper Narragansett Bay of the Atlantic Ocean. Together with its two main tributary branches, the North Branch Pawtuxet River and the South Branch Pawtuxet River, it drains a watershed of 231.6 square miles (600 km2), all of which is in the state of R.I.