The museum opened in 1977 as a local branch of the Ross and Cromarty Heritage Society, the project of Sylvia Murdoch, her husband Morton, and a small group of volunteers including Kay Matheson, one of the four students who in 1950 had removed the Stone of Scone from Westminster Abbey. The committee converted part of an old farm steading in Achtercairn to house a growing collection of objects donated by local people, archaeology, fishing gear, croft furniture, things that risked disappearing as the working life of the parish changed. A second wing was converted the following year as the displays expanded, the library extension was added in 1987, and an extra room was built in 1988 specifically to house the rotating lens recovered from Rua Reidh Lighthouse. By the 2010s, the building had simply run out of room.

In December 2016, the Gairloch Heritage Museum secured a grant of £725,600 from the Heritage Lottery Fund to convert the nearby Cold War bunker into its new home. The project depended on matching contributions from public trusts, private foundations, and community fundraising. The total bill came to roughly £2.4 million, raised by the museum board and volunteers working through five years of jumble sales, sponsored walks, application forms, and patient persuasion. The architects cut careful openings into walls designed to survive a near miss from a nuclear weapon. They removed interior partitions to create exhibition halls. They kept the original heavy blast doors as visible architectural features, a daily reminder of what the building had originally been designed to do. The new museum opened in July 2019, formally inaugurated by The Princess Royal.

The centrepiece of the collection is the Gairloch Stone, a Class I Pictish stone carved with a salmon and discovered locally in 1880. It is one of the very few Pictish stones found on the west coast of Scotland and, geographically, the westernmost example. The Poolewe Hoard, a rare Early Iron Age bronze hoard, is displayed nearby. The original Hyperradiant Fresnel lens from Rua Reidh Lighthouse, a beautifully engineered prism of glass and brass, sits in its own room. A replica croft house from over a century ago shows how Gairloch's tenants actually lived; interactive displays cover the natural history of Wester Ross, the fishing economy, the Gaelic culture of the parish, and the social history that has shaped the present village.

The Art Fund's Museum of the Year award has traditionally gone to a single winner. In 2020, with the Covid pandemic devastating the museum sector, the prize money was increased to £200,000 and the format changed to five winners chosen for community impact rather than institutional weight. Gairloch Museum was among them, recognised for proving that a small Highland community could turn a redundant nuclear bunker into one of the most thoughtfully curated local museums in Britain. The Guardian headline ran: 'Revamped nuclear bunker wins museum of the year award.' What the headline didn't say was that the building, the collection, and the staff are all volunteer-driven, run on grant funding and community persistence, and serve a parish whose total population is under a thousand.