The Niangua River /naɪˈæŋɡwə/ is a 125-mile-long (201 km) tributary of the Osage River in the Ozarks region of southern and central Missouri in the United States. Via the Osage and Missouri rivers it is part of the watershed of the Mississippi River. Niangua River has the name of Niangua (or Nehemgar), an Indian tribal leader. The name is said to mean "bear".