Born on 26 April 1710 in Strachan, near Banchory, Kincardineshire, the son of the Reverend Lewis Reid (1676–1762) and his first wife, Margaret, née Gregory (1673–1732).
He attended the parish school in Kincardine O'Neil for two years and then transferred to the Aberdeen grammar school in April 1722 before entering the class of the professor of Greek, Thomas Blackwell the younger, at Marischal College the following October. After studying at the University of Aberdeen, Reid entered the ministry in New Machar in 1737.
In 1752 he was given a professorship at King's College, Aberdeen, where he wrote An Inquiry Into the Human Mind on the Principles of Common Sense (published in 1764). Shortly afterwards he was given the prestigious Professorship of Moral Philosophy at the University of Glasgow when he was called to replace Adam Smith. He resigned from this position in 1781.
In his day and for some years into the 19th century, Thomas Reid was regarded as more important than David Hume.
The Reid Burnett School, (in what is now the Banchory Burgh Offices), was founded by one of his relatives and three generations of his forefathers were the ministers of Banchory Parish Church.