John Barbour may have been born around 1320 if the record of his age in 1375 as 55 is correct. His birthplace is not known, though Aberdeenshire and Galloway have made rival claims.
Barbour's first appearance in the historical record comes in 1356 with promotion to the archdeaconry of Aberdeen from a post he had held for less than a year in Dunkeld Cathedral. It is inferred from this that he was also present in Avignon in 1355. In 1357, when David II returned to Scotland from exile and was restored to active kingship, Barbour received a letter of safe-conduct to travel through England to the University of Oxford. He subsequently appears to have left the country in other years coincidental with periods when David II was active king.
After the death of David II in 1371, Barbour served in the royal court of Robert II in a number of capacities. It was during this time that he composed, The Brus, receiving for this in 1377 the gift of ten pounds Scots, and in 1378 a life-pension of twenty shillings. He held various posts in the king's household. In 1372 he was one of the auditors of exchequer and in 1373 a clerk of audit.
The only biographical evidence for his closing years is his signature as a witness to sindry deeds in the "Register of Aberdeen" in 1392. According to the obit-book of St Machar's Cathedral, Aberdeen he died on 13 March 1395 and state records show that his life-pension was not paid after that date. Barbour made provision for a mass to be sung for himself and his parents, an instruction that was observed in the Kirk of St Machar until the Reformation.