The lighthouse bears the name of Major-General Sir George Charles d'Aguilar, a British officer who commanded forces in Hong Kong in the 1840s during the early years of colonial rule. The cape itself carries his name too, and the lighthouse simply extended that designation to the sea.

Construction was completed and the light first entered service on 6 April 1875. The technology was state of the art: a fixed dioptric first-order Fresnel lens, a system that uses concentric glass rings to bend and concentrate light into a powerful beam. The focal plane sat 200 feet above sea level, high enough to be seen in clear weather at a range of 23 nautical miles. For merchant ships and passenger steamers threading the South China Sea toward Hong Kong harbor, the white beam at Cape D'Aguilar was a reliable landmark — a signal that landfall was close.

Twenty-one years after Cape D'Aguilar began operation, a more powerful lighthouse opened on Waglan Island, to the southeast. The Waglan Island Lighthouse, better positioned to cover the shipping approaches from the open Pacific, rendered the Cape D'Aguilar light unnecessary. In 1905, the light was removed. Its first-order Fresnel lens was transferred to the Green Island Lighthouse, on the opposite side of the harbor, where it replaced a smaller fourth-order lens.

Cape D'Aguilar went dark. For seventy years the tower stood at the cape without purpose, preserved by its own solidity and by the difficulty of dismantling masonry built to last. Then, in 1975, the lighthouse was returned to service with an automated system — no keeper required, no daily maintenance, just a steady signal going out over the dark water. It has been lit ever since.

Today the structure stands 9.7 meters tall and is a declared monument of Hong Kong, one of five pre-war surviving lighthouses in the territory. The others are the two on Green Island, the Waglan Island Lighthouse, and the Tang Lung Chau Lighthouse — both Waglan and Tang Lung Chau are also declared monuments.

Hong Kong's declared monuments are buildings and structures deemed to have sufficient historical, cultural, or architectural significance to warrant legal protection against demolition or alteration. The designation is not given lightly. Cape D'Aguilar Lighthouse earned it through age, rarity, and the quality of its original construction.

Pre-war buildings in Hong Kong were tested by occupation, aerial bombardment, and decades of tropical humidity. Many did not survive. The five pre-war lighthouses that remain — including Cape D'Aguilar — are among the oldest standing structures in the territory. The lighthouse's design reflects standard British colonial maritime engineering of the late nineteenth century: solid masonry, a lantern room at the top, and a form that has barely needed modification in 150 years. The Fresnel lens is gone, replaced by modern optics, but the tower itself is original.

Cape D'Aguilar sits at the southeastern corner of Hong Kong Island, where the land runs out and the South China Sea opens wide. Ships have passed this point for centuries — trading junks, colonial steamers, container vessels, fishing boats — and the lighthouse's job has always been the same: mark the land so that those at sea know where they are.

The cape now lies within the Cape D'Aguilar Marine Reserve, a protected area established to conserve the remarkable marine biodiversity of these waters. The lighthouse overlooks one of Hong Kong's least-disturbed coastal environments. Swimmers who venture into the reserve find surge channels, sea caves, and underwater rock formations. The lighthouse that once warned ships away from the rocks now stands over a place deliberately kept wild, a quiet reversal of its original mission.