The line from Mettupalayam to Coonoor was opened for traffic on 15 June 1899 during British colonial rule and was later extended to Udgai Hill Station.
The ‘Railway Committee’ was formed with Sir Robert Stanes as the Chairman and Limited Joint Stock Company called the Coonoor Railway Company (Limited) was proposed in 1880.
Later new Nilgiri Railway Company was formed in 1896 to purchase and finish the line.
This line was finally declared open in June 1899, and operated by the Madras Railway under an agreement.
UNESCO designated the Nilgiri Mountain Railway as a World Heritage Site on July 15, 2005.