Henry Conolly was born on 5 December 1806 to Valentine Conolly of 37 Portland Place, London. He and his younger brother Arthur were educated at Rugby School, Warwickshire. Conolly then moved to Madras, and became a writer in the Madras Civil Service from 19 May 1824. He later served in Bellary as principal collector. He served as a translator of Kannada, a cashier and as commissioner for settlement of claims in the Carnatic region.^[1][2][3]

While District Collector and Magistrate of Malabar Conolly helped develop waterways including a canal now known as the Conolly Canal, initiated 1848, and teak plantations. The teak plantation was a pioneering example of systematic forest management. It contained some of the finest pieces of the tropical hardwood teak. The plantations were constructed by the Madras Government for the supply of teak timber to the port of Bombay.^[4][5][6][7] He is also remembered for his planning a coastal waterway in Malabar — what is known today as the Conolly Canal (although the introduction of railways around the time the canal was being completed had eclipsed its importance).^[8]

At about 9p.m. on the evening of 11 September 1855 Conolly was attacked and killed at the Collector's Residence at West Hill Bungalow, Calicut by a small group of Mappilas. Conolly was buried in what is now Conolly Park, near South Beach Road; the headstone of his tomb was moved to the premises of the C.S.I. St. Mary's English Church, Calicut in 1997.^[9] The murderers, Valassery Emalu, Puliyankunnath Thenu (who had escaped from prison at Calicut a month before) and Haiderman, a hairdresser, were eventually tracked down and shot dead by government forces led by Major Haly and Captain Davis (in an encounter after 6 days at large at Edavannappara in Thiruvambadi). The Mappila rebels were using these escaped prisoners to murder Henry Conolly, who had suggested exiling Fazal Pookoya Thangal of Mambrum.^[10]