He graduated MA at Edinburgh in 1654; was minister of Killinchy, County Down, in 1657; continued to preach, in defiance of the bishop, through 1660; was outlawed in 1664; returned to Scotland in 1666; was sentenced to transportation for field-preaching in July 1668, and imprisoned in London; allowed to return to Killinchy in 1670; driven out by the rebellion in 1688; and was finally minister of Anwoth, Wigtonshire from 1689 until death.
He was the third and youngest son of Patrick Bruce of Newtown, Stirlingshire, by Janet, second daughter of John Jackson, merchant of Edinburgh.
In that year John Livingstone of Ancrum, formerly minister of Killinchy, County Down, paid a visit to his old charge, with a view to settle there again.
This he did not do, but on returning to Scotland he looked out for a likely man for Killinchy, and at length sent Bruce with a letter (dated 3 July 1657) to Captain James Moore of Ballybregah "to be communicated to the congregation".
At the Restoration, Bruce's position was very precarious, but he refused a call to Bothkennar, Stirlingshire, in 1660, and though deprived for Nonconformity by Bishop Jeremy Taylor, he continued to preach and administer the sacraments "at different places in the parish, in kilns, barns, or woods, and often in the night".
At length, in 1665 or 1666, Bruce returned to Scotland, not to keep quiet there, for in June 1666 his field preachings procured him a citation before the Lords of the Privy Council in Edinburgh as "a pretended minister and a fugitive from Ireland".
Admitting and defending his practice of preaching and baptising in houses and the fields, he was banished out of His Majesty's dominions of Scotland, England, and Ireland, under the penalty of death.
The end was that his kinsman, the Earl of Elgin, procured for him a writ quashing all past sentences, and he got back to Killinchy with his family in April 1670.
Though Roger Boyle, who had succeeded Jeremy Taylor as Bishop of Down and Connor, instituted proceedings against him and others for preaching without license, Berkeley, the Lord-Lieutenant, and James Margetson, the Primate, intervened, and the Presbyterians were left unmolested.
In 1679 Bruce signed an address presented by the Down Presbytery to the Irish Government, disclaiming any complicity "with the rising of the Scottish Covenanters put down at Bothwell Bridge.