Keppel was the fifth and fourth surviving son of Willem van Keppel, 2nd Earl of Albemarle and his wife Lady Anne Lennox, daughter of Charles Lennox, 1st Duke of Richmond. His older brothers were George Keppel, 3rd Earl of Albemarle, who had succeeded their father as earl, Augustus Keppel, 1st Viscount Keppel, an admiral, raised to the peerage in his own right and the politician and military commander Hon. William Keppel.
After his graduation with a Doctor of Divinity, Keppel was appointed Canon of the Eleventh Stall at St George's Chapel, Windsor in 1754, acting as chaplain first to King George II of Great Britain and then to the latter's son King George III of the United Kingdom. He was consecrated as Bishop of Exeter in 1762 and became Dean of Windsor as well as consequently Register of the Order of the Garter three years later, holding all three posts until his death in 1777.
On 13 September 1758, he married Laura Walpole, sister of Maria, Duchess of Gloucester and Edinburgh and eldest daughter of Hon. Edward Walpole, a son of Robert Walpole, 1st Earl of Orford. They had four children, three daughters and one son. Keppel died in 1777 and his wife survived him until 1813. His daughter Laura was wife of George FitzRoy, 2nd Baron Southampton.
- Debrett, John (1828). Debrett's Peerage of the United Kingdom of Great Britain and Ireland. vol. I (17th ed.). London: G. Woodfall. p. 136.
- Burke, John (1832). A Genealogical and Heraldic History of the Peerage and Baronetage of the British Empire. vol. I (4th ed.). London: Henry Colburn and Richard Bentley. p. 22.
- Collins, Arthur (1812). In Sir Egerton Brydges. Collin's Peerage of England. vol. I. London: T. Bensley. pp. 740–741.
- Haydn, Joseph (1851). The Book of Dignities: Containing Rolls of the Official Personal of the British Empire. London: Longman, Brown, Green and Longman's. p. 351.
- "ThePeerage - Rt. Rev. Hon. Frederick Keppel". Retrieved 25 December 2006.
- Oliver, George (1861). Lives of the Bishops of Exeter and a History of the Cathedral. Exeter: William Roberts. pp. 163–164.
|Church of England titles|
|Bishop of Exeter
1762 – 1777
|Dean of Windsor