She was born at Largs, Ayrshire. Married on 19 February 1760 to Sir Walter Maxwell, she was widowed at 19 and lost her only son weeks later. She experienced a religious conversion and became a lifelong member of the Methodist society at Edinburgh. In 1787 she claimed the experience of 'Christian perfection'. She lived frugally and was generous in her support of philanthropic causes. John Wesley was often her guest and she was most generous to the itinerants stationed in Edinburgh, where she founded a free day school in 1770 and Sunday Schools in Edinburgh and London. She also supported students training for the evangelical ministry at Edinburgh University. Lady Glenorchy, a long-standing friend despite their doctrinal disagreements, made Lady Maxwell her executrix in establishing a Calvinistic chapel in Bristol in spite of Wesley's grieved opposition. She died in Edinburgh on 2 July 1810 and is buried in the Greyfriars Kirkyard.