He was born in Greenlaw, Berwickshire, and began studying at the University of Edinburgh at the age of 13. He graduated in 1826 and commenced work as a tutor in Orkney. He was ordained by the Church of Scotland at North Ronaldshay in Orkney in 1830 and remained there for six years. After that time, he ministered at the Extension Church at Bridgeton, Glasgow, before being translated in 1840 to Salton, East Lothian.
After the Disruption of 1843, Fairbairn joined the Free Church of Scotland. In 1852 he became assistant to Prof Maclagan at the Free Church Theological College in Aberdeen and in 1853, the General Assembly appointed him as successor to Maclagan as Professor of Theology. He then lived at 25 Bon Accord Terrace in Aberdeen.
When the Free Church College was founded in Glasgow in 1856, Fairbairn became Professor of Church History and Exegesis—positions and was made Principal the following year. He held these positions until his death in 1874. He was elected Moderator of the General Assembly in 1864, succeeding Rev Roderick McLeod, and was succeeded in turn in 1865 by Rev James Begg.
In 1845, Fairbairn wrote The Typology of Scripture. MacLehose (1886) noted that this was "one of the most important theological works of its day," and suggested that it "appeared at a time when Scotland was singularly barren in theological scholarship, and gained for its author a great reputation, not only in his own country but also in England and America."
Fairbairn's work on typology was followed by Prophecy viewed in its Distinctive Nature, its Special Functions, and Proper Interpretation (1856) and Hermeneutical Manual; or, Introduction to the exegetical study of the Scriptures of the New Testament (1858). He also wrote commentaries on Ezekiel and the Pastoral epistles, and edited the Imperial Bible Dictionary.
Fairbairn was "large and imposing in appearance," but "modest and retiring in his habits and feelings." He was married three times, but little is known of his private life because Fairbairn "asked his friends not to allow his biography to be written, and destroyed letters and other documents which might have led them to a disregard of his wish."
Walker (1964) suggested that Fairbairn's "zeal for ascertaining and propagating the truth of God ... continued steadfastly with all the vigour of his powerful intellect until the closing days of his life."
He died at home, 13 Elmbank Crescent, in west Glasgow.
His Glasgow home was demolished in the late 20th century to build a multi-storey car park.
He was married three times: Margaret Pitcairn in 1833; Mary Playfair in 1839; and Frances Turnbull in 1861.
- MacLehose, James (1886). "Patrick Fairbairn". Memoirs and Portraits of One Hundred Glasgow Men. pp. 133–134. Retrieved 11 December 2010.
- Wylie, James Aitken (1881). Disruption worthies : a memorial of 1843, with an historical sketch of the free church of Scotland from 1843 down to the present time. Edinburgh: T. C. Jack. pp. 245–252. Retrieved 18 August 2018.
- Aberdeen Post Office Directory 1855
- Walker, Charles (1964). "Biographical Introduction". In Patrick Fairbairn (ed.). The Interpretation of Prophecy. The Banner of Truth Trust. pp. xvii–xxiii.
- Glasgow Post Office Directory 1874
- Ewing, William Annals of the Free Church