The Mitta Mitta River is a major tributary of the Murray River in Australia and the source of approximately 40% of the Murray's flow.

The river's headwaters include Victoria's highest mountain, Mount Bogong, and wind their way north about 100 kilometres, gradually slowing before joining the Murray east of Albury.

The river's flow is heavily modified by the presence of two major dams, the Dartmouth Dam and the Hume Dam. Upstream of the Dartmouth Dam, the river flows swiftly through near-pristine forest. Below the dam, it travels more sedately through flatter, cleared farming country (some of which is now irrigated using its water, though most continues downstream to meet the needs of irrigators there).

The junction with the Murray is now submerged beneath the waters of Lake Hume for a large part of the time.

The river valley used to flood on a nearly annual basis, but the completion of Dartmouth Dam in the 1970s largely eliminated the floods.

The Mitta Valley contains four small towns:

• Mitta Mitta
• Eskdale
• Dartmouth
• Tallangatta