As early as 1848, a level of protection was given by the colonial government to the primary forests of Bukit Timah for fear of over-logging and depletion of timber resources. However, it was not until 1883 when the British Colonial Government of the Straits Settlements officially established Bukit Timah Nature Reserve as the first nature reserve in Singapore. During the Japanese occupation, Kwan Koriba, a botanist from Kyoto University was brought in to oversee the parks and reserves on the island and in 1951, the reserve came under the protection of the Nature Reserve Ordinance (the National Parks Act).
In 1986, the Bukit Timah Expressway (BKE) was completed along the reserve's eastern perimeter, separating the Bukit Timah Nature Reserve from the Central Catchment Nature Reserve, where the major remaining rainforest of Singapore lies. While tigers no longer roam the hills of Bukit Timah and much of the pristine rainforest is gone as Bukit Timah has undergone industrial and urban developments over the past hundred years, what is left are 163 hectares of untouched primary rainforest.