Holy Trinity Church is a medieval building situated next to Millom Castle near the town of Millom, Cumbria, England. It is an active Anglican parish church in the deanery of Furness, the archdeaconry of Westmorland and Furness, and the diocese of Carlisle. Its benefice is united with those of St George, St Anne, Thwaites, and St Luke, Haverigg. The church is recorded in the National Heritage List for England as a designated Grade I listed building.

Millom is a town and civil parish on the north shore of the estuary of the River Duddon in southernmost Cumberland, Cumbria, England. It is situated just outside the Lake District National Park, about six miles north of Barrow-in-Furness and 26 mi (42 km) south of Whitehaven.