A mile and a half inland from Amlwch's harbour stands Parys Mountain, where in 1768 a vein of copper was uncovered that briefly made Anglesey the largest copper producer in the world. The ore had to leave by sea, and the only harbour close enough was the narrow rocky cleft at Porth Amlwch - a slit of water barely wide enough for a single vessel to enter. By the 1790s the harbour was choked with ships waiting to load. An Act of Parliament in 1793 authorised the first two piers, and on top of those piers went two octagonal houses with lanterns poking through their roofs: the first lighthouses, described in a contemporary mariners' guide as 'small white houses displaying lights at night.' The volume of traffic was extraordinary for the size of the harbour.

In 1816 the harbour was extended again, this time with a 46-metre outer pier to give vessels more shelter from north-easterly gales. A new light went up on the pier head the following year, raised 8.5 metres above the high-water mark. That tower was replaced by the present one in 1853, and the current lantern came later still. The pattern says something about how hard the sea worked on this pier - few small harbour lights have been rebuilt four times in seventy years. Each replacement had to be tougher than the last, and the 1853 tower, with its battered profile and finely cut stone, was built to outlast everything that came before. So far it has.

Copper production at Parys Mountain peaked in the 1780s and was already in steep decline by the mid-19th century. By the time the present lighthouse was built, the harbour was finding new work in shipbuilding and ship repair, with one of the largest dry docks in northwest Wales tucked just inside the inner basin. The dry dock survives as part of Amlwch's restored heritage harbour. The lighthouse stands at the end of the outer pier, weathered but still recognisably the same square tower that 19th-century captains aimed for through the dark. Trinity House records list it as a Grade II listed structure. Few small lighthouses anywhere in Britain can claim to have served so global a trade from so small a footprint.