The length of the river is 686 kilometres (426 mi). The area of its drainage basin is 42,500 square kilometres (16,400 sq mi). The Klyazma River usually freezes up in November and stays under the ice until mid-April, although in faster moving stretches ice-free water occurs until the air temperature drops below minus 10 °C (50 °F).
Its main tributaries are the Ucha, Vorya, Kirzhach, Peksha, Nerl, Uvod, Teza, Lukh, Sudogda and Suvoroshch.
The Klyazma is navigable within 120 kilometres (75 mi) from its estuary and in the area of the Klyazminskoye Reservoir. The cities of Gorokhovets, Mendeleyevo, Pavlovsky Posad, Vladimir, Kovrov, Shchyolkovo, Losino-Petrovsky, Noginsk, Orekhovo-Zuyevo, Sobinka and Vyazniki are located on the shores of the Klyazma River.