The Nilgiris District is in the southern Indian state of Tamil Nadu. Nilgiri (English: Blue Mountains) is the name given to a range of mountains spread across the borders among the states of Tamil Nadu, Karnataka and Kerala. All types of single use plastics are banned in Nilgiris District.

The Nilgiri Hills are part of a larger mountain chain known as the Western Ghats. Their highest point is the mountain of Doddabetta, height 2,637 m. The district is contained mainly within the Nilgiri Mountains range.

The administrative headquarters is located at Ooty (Ootacamund or Udhagamandalam).

Nilgiris District ranked first in a comprehensive Economic Environment index ranking districts in Tamil Nadu (not including Chennai) prepared by the Institute for Financial Management and Research in August 2009.

Tea and coffee plantations have been important to its economy. As of 2011, the Nilgiris district had a population of 735,394, with a sex-ratio of 1,042 females for every 1,000 males. It is the first plastic free district in Tamil Nadu State.