Son of Donald Macpherson of Breakachie, and Christian Macpherson. In 1759 he became an ensign in the 78th Foot Regiment (known as Fraser's Highlanders). In 1760 he was promoted to Lieutenant. His regiment was disbanded in 1763, but he returned to active service in August 1765, in a company headed for Africa. The next year he became seriously ill and died in Africa on December 5, 1766.
Boswell met Macpherson in Berlin on July 5, 1764, and described him as "a fine, honest, spirited fellow." They spent a lot of time in each other's company during Boswell stay in the city.