The two brothers left Haileybury and Henry went to a private tutor at Medmenham near Henley who encouraged him in Zoology and then went to Exeter College, Oxford where he studied under Edwin Ray Lankester and George Rolleston while also taking an interest in botany and geology under the influence of Marmaduke Lawson and Joseph Prestwich.

He then joined the British Museum in the botany department to replace Henry Trimen who had moved to Ceylon.

In 1887 he joined the Royal Society expedition with George Ramage to the island of Fernando de Noronha off Brazil, and published on the collections on returning.

[7] Ridley established the methods for harvesting latex from Pará rubber plants which had been introduced ten years earlier by Sir Hugh Low[8] apart from starting a zoological section in the gardens in 1870.

[7] Ridley was also largely responsible for establishing the rubber industry on the Malay Peninsula,[10] where he resided for twenty years.

[14] It has been claimed that the olive ridley sea turtle is named after him, but this has been questioned as there is insufficient evidence.

[14] In 1913, botanist Rudolf Schlechter published Ridleyella, a monotypic genus of flowering plants from the orchid family, Orchidaceae.

[16][17] Then in 1998, botanists A.Weber & B.L.Burtt published Ridleyandra, a genus of about 30 species of flowering plants from Borneo, Malay and Thailand, belonging to the family Gesneriaceae and it also was named in Ridley's honour.