He served as clerk in the Foreign Office from 1872 to 1876.
Chirol began as correspondent and editor of The Times travelling across the globe writing about international events. He succeeded Donald Mackenzie Wallace as director of foreign department of The Times in 1899. He retired in 1912.
Deprecatory comments in Chirol's book Indian Unrest resulted in a civil suit being brought against him in London by Bal Gangadhar Tilak, who advocated Indian independence. Tilak lost the suit.
After two decades as a journalist, Chirol joined the Foreign Office as a diplomat and subsequently was knighted for his distinguished service as a foreign affairs advisor.
A series of 20 articles by Chirol that appeared in The Times in 1902 and 1903 under the heading The Middle Eastern Question helped to bring the term Middle East into common usage.