Born with the courtesy title of Lord Lansdown in 1661, he was the eldest son of John Granville, 1st Earl of Bath and his wife, the former Jane Wyche.
On 19 November 1680, Granville was elected as Member of Parliament for Launceston following the by-election caused by the death of Sir John Coryton, Bt.
In 1683, he fought in the Battle of Vienna on the Habsburg side and was created a Count of the Holy Roman Empire for his services, on 27 January 1684.
Granville returned to Parliament after being elected MP for Cornwall in 1685 and was also appointed ambassador to Spain that year.
[1] 10 May 1691 (New Style), he married Isabella, the sister of Henry de Nassau d'Auverquerque, 1st Earl of Grantham.