Through his father's interest in Devon and Cornwall, he was returned as Member of Parliament for Plympton Erle at a by-election in 1742 as a Government supporter.

[1] Edgcumbe was a heavy gambler, losing "daily twenty guineas" at White's.

He was given a secret service pension of £500 a year by Henry Pelham to provide for him.

Dissatisfied with subsisting on Government charity, he unsuccessfully made an application to Pelham for employment, rather than a pension, in 1752.

Succeeding his father in 1758, he was appointed Lord Lieutenant of Cornwall in 1759 and recorder of Plympton Erle.