The name Forest Hill, originally simply ’The Forest’, referred to the woodland which once covered the area and which was a relict of the Great North Wood.

While in 1809, the Croydon Canal opened, however, the large number of locks meant it was not a commercial success, and it was bought by the London & Croydon Railway Company (L&CR) who used the alignment to construct the London Bridge to Croydon railway line. The local station was opened by the London & Croydon on 5 June 1839, as Dartmouth Arms (the name of the local inn).

When the Crystal Palace was moved from Hyde Park to Sydenham in 1854, many large homes were built on the western end of Forest Hill along with Honor Oak. In 1884, London’s oldest swimming pool was constructed on Dartmouth Road. The tea merchant Frederick Horniman built a museum to house his collection of natural history artifacts. He donated the building and its gardens to the public in 1901 and this became the Horniman Museum.

In 1844, the station was chosen by the L&CR as the northern terminus for Phase 1 of an experimental atmospheric railway to West Croydon. In July 1846, ’atmospheric’ working was abandoned.