He was born in the Free Church manse in Dollar, Clackmannanshire, in 1869, the son of Rev George Halley Knight and his wife Marianne Sommerville, and grandson of the Rev George Fulton Knight and nephew of the Rev William Angus Knight.
He began preaching at the Free Church of Scotland in Auchterarder around 1892. In 1900, on the creation of the United Free Church of Scotland he moved to St Leonards-in-the-Fields Church, Perth. He was elected a fellow of the Royal Society of Edinburgh in 1901. His proposers were Malcolm Laurie, Robert Kidston, William Evans Hoyle and John Gray McKendrick. In 1907 he was living at 9 St Leonards Bank on the South Inch in Perth.
In 1928 he took on the role of general secretary to the National Bible Society of Scotland. He died suddenly on 2 May 1937.
He married Annie Baillie Adamson, daughter of Rev Thomas Adamson of the Free Church of Scotland.
His namesake grandson, generally known as G. A. F. Knight in literature, was also a Biblical scholar and served as the moderator of the General Assembly of the Presbyterian Church of New Zealand in 1974.
- The Marine Mollusca of Port Stewart, Northern Ireland (1901)
- Greatheart (1914)
- Nile and Jordan (1921)
- Archaeological Light on the Early Christianizing of Scotland (1933)
- Ewing, William Annals of the Free Church
- Biographical Index of Former Fellows of the Royal Society of Edinburgh 1783 – 2002 (PDF). The Royal Society of Edinburgh. July 2006. ISBN 0 902 198 84 X.
- Transactions of the Natural History Society of Glasgow, 1907
- "From G.A. Frank Knight, 52 Sardinia Terrace Glasgow. | The National Archives". Discovery.nationalarchives.gov.uk. Retrieved 2020-02-23.