In 1621 Manaton was elected Member of Parliament for Bossiney. He was elected MP for Tregoney in 1624. In 1627, he was called to the bar at Lincoln's Inn. He became a master of chancery extraordinary and recorder of Launceston.
Manaton was next elected as MP for Launceston in April 1640 for the Short Parliament. He was re-elected in November 1640 for the Long Parliament and sat until 1641 when he was disabled for supporting King Charles I. Manaton was created D.C.L. at Oxford University on 21 March 1644. He entertained King Charles at his house in 1644.
Manaton died in 1651 and was buried at South Petherwin, where his monument displayed the arms of Manaton and Reskymer, and Manaton and Edgcombe.
- Records of the Anglo-Norman house of Glanville Appendix (Arms of Glanville - 5th Coat)
- 'Alumni Oxonienses, 1500-1714: Mab-Marygold', Alumni Oxonienses 1500-1714 (1891), pp. 956-982. Date accessed: 5 May 2012
- Willis, Browne (1750). Notitia Parliamentaria, Part II: A Series or Lists of the Representatives in the several Parliaments held from the Reformation 1541, to the Restoration 1660 ... London. pp. onepage&q&f=, false 229–239.
- James Venning An illustrated postal directory with map and historical notices, of twenty parishes in East Cornwall, for the new century. From A.D. 449 to 1901
- Manaton 2 Wills of the parishes of Linkinhorne, St Ive and South Hill - Will of Ambrose Manaton
- David Hayton, Eveline Cruickshanks, Stuart Handley The House of Commons, 1690-1715, Volume 2
|Parliament of England|
| Member of Parliament for Tregoney
With: Peter Specott
Sir Henry Carey
Parliament suspended since 1629
| Member of Parliament for Launceston
With: Bevil Grenville 1640
William Coryton 1640–1641