Son of David Laing Montgomerie (d. 1752)1 and Veronica Boswell (d. 1742), and as such a first cousin of James Boswell. Brother of Margaret Montgomerie, Boswell's wife, although their marriage was not until after James Montgomerie's death.
Montgomerie married Jean Maxwell, daughter of Sir John Maxwell of Nether Pollock, but died in 1767 without issue. He was succeeded by his eldest sister, Elizabeth.
- 1David was the son of Jean Montgomerie and Alexander Laing, Rector of Donaghadee. He inherited Lainshaw from his uncle James Montgomerie who died ca. 1726 without issue.