The East Siberian Mountains or East Siberian Highlands (Russian: Восточно-Сибирское нагорье, romanized: Vostochno-Sibirskoye Nagorye) are one of the largest mountain systems of the Russian Federation. They are located between the Central Yakutian Lowland and the Bering Strait in Northeast Siberia. The area of the East Siberian Mountains has a very low population density. The territory of the mountain system is one of the Great Russian Regions.

In some areas of the East Siberian Mountains, such as the Kisilyakh Range and the Oymyakon Plateau there are kigilyakhs, the rock formations that are highly valued in the culture of the Yakuts.

The East Siberian System consists of several separate sections of mountain ranges rising to the north and south of the Arctic Circle. The main group of ranges stretches for a distance of nearly 3,000 kilometres (1,900 mi) from the Lena River valley to Cape Dezhnyov, at the eastern end of the Chukotka Peninsula. Although it reaches a width of roughly 1,200 kilometres (750 mi), the highland region is almost cut in half by the East Siberian Lowland that stretches to the north in the central area. To the southwest the boundary is not clearly delimited, as it overlaps with the system of the South Siberian Mountains. Owing to the mountainous terrain, large swathes of the East Siberian system are uninhabited. The largest city is Magadan.

The main rivers of the vast region are the Yana, Indigirka, Kolyma and its tributary Omolon, as well as the Anadyr.

The world's lowest temperatures for inhabited places have been recorded in this region. In the south of the East Siberian Mountain System lies the area of the famous Oymyakon Depression, where record low temperatures are registered, even though the region is about 3,000 kilometres (1,900 mi) to the south of the geographic North Pole.

The lower elevations of the ranges, as well as the valleys, are largely covered by taiga. Rivulets and humid areas in lower altitudes of most of the ranges of the system provide a habitat for the Siberian Salamander, a species known for surviving deep freezes —as low as −45 °C (−49 °F).

• Cherskii-Kolyma mountain tundra
• Chukchi Peninsula tundra
• Northeast Siberian taiga

• Moma Natural Park