In October 1840, he was appointed Chinese secretary to the British superintendent of trade in China.
[1] During the Opium War, he worked under Rear-Admiral George Elliot and Sir Henry Pottinger.
In the following years, he held a number of important consular positions in Chinese treaty ports such as Fuzhou, Shanghai (as H.M. Consul), Hangzhou and Hankou.
Medhurst distinguished himself as a prominent advocate of gunboat diplomacy to defend what he considered to be British interests in China.
[1] He moved back to England in 1884,[1] and died at Torquay on 26 December 1885, leaving another son and at least two daughters.