A letter dated 28th August 1813 from Vice Admiral Thornborough of Trent, Cork Harbour, was read to the Ballast Board on 2 September 1813 in which he pointed out the danger vessels were put to frequenting Cork Harbour for want of a light house at the entrance to the harbour. He recommended that the Corporation for Preserving and Improving the Port of Dublin (the Ballast Board) erect a revolving light at or near Roche's Tower. The Board referred Vice Admiral Thornborough's letter to Trinity House in London.
Three months later Trinity House replied stating that a light would be highly advantageous. It need not be of great magnitude but should be readily distinguishable from Old Head of Kinsale. The following month, January 1814, the Treasury in London gave their consent to building a lighthouse, and in February the Lord Lieutenant in Dublin Castle signified his approbation.
George Halpin, the Board's Inspector Works and Inspector of Lighthouses, was instructed to make necessary enquiries relative to the ground at Roche's Point. In March 1814 he reported to the Board stating that he agreed with Vice Admiral Thornborough for the expeditious erection of a lighthouse on Roche's Tower which was 35 feet (10.6m) high and strong enough to support a lantern. The base of the tower was 46 feet (14.0m) above high water. The light should be fixed with a distinctive colour to seaward so as not to be confused with other lights. The Tower belonged to Edward Roche who for some time had been living in France. Mr Halpin was informed by Roche's agent, Mr Fitzgibbon of Cork, that Mr Roche should be returning soon. The Board ordered that their Law Agent take the necessary steps for an inquisition to ascertain the value of the Tower and one acre of land.
Early in April 1814 Mr Fitzgibbon wrote to the Board stating that he had no authority to sell or dispose of any or part of the estates of Edward Roche Esq. and Mr Roche had resided for some years as a prisoner of war in Naples, Italy. Recent political activities had however set him free and he should be back in Cork in the early summer. The Board ordered that the inquisition should be delayed.
Edward Roche of Trabolgan was delayed too. It was February 1815 when he wrote to the Corporation on the subject of converting the Tower into a lighthouse. He stated that the Tower had been built (presumably by himself or his father) as a banqueting and pleasure house. It was also the only place where he could get a sight of shipping and Cork Harbour.
He also stated that at great expense he had refurbished the Tower so he could spend as much of his time in it as he could. During the American War of Independence (1776-83) a certain General Massey in Ireland had approached him and pointed out that the Tower was absolutely necessary for the defence of the harbour so Roche rented it to the Government for a period of 10 years at 100 guineas per annum. Using this as a basis and pointing out that the value of land had risen by 80% he said he would be content with 100 guineas per annum and that the lease should be for a corn-rent to protect his heirs against depreciation.
Roche was quickly written to by the Board stating they could not accept his proposals as the rent of 100 guineas was too much, also the Board required a lease for ever and unless such was given and the rent greatly reduced the Board would, by Law, have to have the premises valued by a jury.
Needless to say Roche was very upset with the Board's reply and threatened to take his case to the House of Commons. With this attitude the Board ordered the Law Agent to prepare steps for an inquisition. During April 1815 the Law Agent informed the Board that the inquisition was to be held in Cove (Cobh) on 5 June, the result of which was that the Tower was valued at £160 and the ground at £1,266, making a total of £1,426.
The purchase of the land and Tower was completed in January 1816 but not without Roche objecting to searches for encumbrances and enquiring about the delay in receiving the valuation of his ground.
In the meantime the Board instructed Inspector Halpin to take measures for completing a number of works, among them Roche's Point.
Trinity House sanctioned the light on 27 June and work went ahead on a new separate lighthouse tower and Keeper's dwelling designed by George Halpin and built under his supervision by workmen of the Board close to Roche's Tower.
By February 1816 Inspector Halpin reported that the Keepers' habitations were nearly completed but there seems to have been delay in supplying the light apparatus consisting of ten Argand oil lamps and ten catoptric reflectors. These did not arrive until late April 1817 but as soon as work went ahead to install them a Notice to Mariners was issued stating that the light would be established on 4th June 1817, showing red to sea and bright to the Cove of Cork. The tower was, and still is, painted white. The light was 92 feet (28.0m) above high water and the tower, which was similar to towers also being built at Fanad Head, Co. Donegal and Mutton Island off Salthill, Co. Galway, was 36 feet (11.0m) overall height and had an internal diameter of only 6 feet (1.8m).
This small lighthouse tower was not conducive to a major harbour of refuge and port and in 1835 it was replaced by the present larger tower which is 49 feet (15m) in height with an internal diameter of nearly 12 feet (3.6m). The original small tower was taken down and complete with lantern lamps and reflectors was carried to Duncannon in two small vessels and erected as the Duncannon North Light forming a rear leading light with Duncannon Fort Light in 1838.
In 1864 a single fixed holophotal light was placed in front of and below the lighthouse on the cliffs, marking the Daunt Rock, and in 1865 the fixed main light was replaced by a revolving optic showing a red light once every minute.
On the 8th August 1932 the auxiliary fixed white light sector (016°-033°) over the Daunt Rocks was permanently discontinued and replaced by an additional red sector in the main light covering the same arc and having the same character as the main light.
In January 1949 the siren fog signal was replaced by a diaphone fog signal with a character of a two second blast every 30 seconds. From April 1978 the light was exhibited in poor visibility during daylight house when the fog signal was sounding. On 11 January 2011 the fog signal was permanently disestablished. The light continues to be exhibited in conditions of poor visibility during daylight hours.
On 15 August 1993 the character of Roches Point Lighthouse was changed to Fl WR 3s (flashing white and red every three seconds) with a range of 20 nautical miles for the white light and 16 nautical miles for the red light. Its sectors are as follows:
White: 292°-016° (084°)
Red: 016°-033° (17°)
White: 033°-159° (126°)
On 1 April 1995 Roches Point Lighthouse was converted to automatic operation. The diaphone fog signal was replaced by an electric horn fog signal with a range of four nautical miles. The Keepers were withdrawn and the station was placed in the care of an Attendant with the aids to navigation monitored via a telemetry link from Dun Laoghaire.