Their name comes from the cardamom spice grown in much of the hills' cool elevation, which also supports pepper and coffee.

The Western Ghats and Periyar Sub-Cluster including the Cardamom Hills are UNESCO World Heritage Sites.

They cover about 2,800 km2 of mountainous terrain with deep valleys, and includes the drainages of the west flowing Periyar, Mullayar and Pamba rivers.

There are several named peaks over 2,000 metres (6,600 ft) in the mountain range including: The hills experience average daily temperatures of 15 °C in winter to 31 °C in summer (April–May).

On the western side, two-thirds of the precipitation is received during the southwest monsoon from June to September.

The Meghamalai reserve forest, also contiguous with Periyar, is proposed to be the 600 km2 Meghamalai Wildlife Sanctuary to protect several threatened species including: Bengal tiger, Indian elephant, Nilgiri tahr, lion-tailed macaque, slender loris, grizzled giant squirrel, Salim Ali's fruit bat, great Indian hornbill, Hutton's pitviper and Vindhyan bob butterfly.

[7] According to the report dated 7 September 2005[8] of the Central Empowered Committee, appointed by the Supreme Court of India, the status of the Cardamom Hill Reserve is forest, and the extent is about 334 sq miles.

The CEC concludes that in the Cardamom Hill Reserve, which still holds dense forest, illegal assignment of lands or grant of patta, illegal sales of land, large scale encroachments, transfer and sale of land and consequent deforestation, by the rich, the powerful and the influential, continue unabated in gross violation of the Forest (Conservation) Act, 1980 and this Honourable Court’s order dated 12 December 1996.