Junín is a region in the central highlands of Peru. Its capital is Huancayo.

The region has a very heterogeneous topography. The western cordillera located near the border with the Lima Region, has snowy and ice covered peaks. On the east, there are high glacier valleys which end up in high plateaus (Altiplano). Among them is the Junín Plateau that is located between the cities of La Oroya and Cerro de Pasco.

The Mantaro Valley becomes wider before Jauja up to the limit with the Huancavelica Region. This area concentrates a large share of the region's population. Towards the east, near the jungle, there is an abundance of narrow and deep canyons, with highly inclined hillsides, covered by woods under low-lying clouds.

The Huaytapallana Cordillera is located in the south central area of the region. This cordillera holds a great fault which is the reason earthquakes happen in the area. The upper jungle, with valleys of great length, modelled by the Tulumayo, Paucartambo, Perené and Ene rivers, is located on the eastern side of the region.

Lake Junín, the largest lake entirely within Peru, is located in the region, except for its northernmost tip which belongs to the Pasco Region.

Junín Region is also home to Mount Toromocho.The Junín Region borders the regions of Pasco on the north, Ucayali on the northeast and Cusco on the east. The Mantaro River marks the region's border with the Ayacucho and Huancavelica regions on the south and on the west, it is bordered by the Lima Region.

The Junín Region has an average annual temperature of 13.1°C (56°F), a maximum high of 17°C (62°F) and a minimum low of 0°C (32°F).

The rainy season runs from November to April, and from December to March in tropical areas.