[3] Edgcumbe was returned unopposed as MP for Cornwall at a by-election on 25 June 1701 but never took his seat as Parliament had been prorogued.

He was re-elected at the 1705 English general election in a contest, and voted for the Court candidate as Speaker on 25 October 1705.

Edgcumbe voted for the motion ‘No Peace Without Spain’ on 7 December 1712 and divided against the French commerce bill on 18 June 1713.

He was returned again at the 1727 British general election, and was appointed a Privy Councillor for Ireland on 28 November 1727.

In 1742, Edgcumbe was appointed Lord Lieutenant of Cornwall and Chancellor of the Duchy of Lancaster, which posts he held for the rest of his life.