Robert Dinwiddie moved from mercantile work into imperial customs administration, serving in Bermuda and then as surveyor general for Britain's southern American colonies. He investigated revenue collection and obtained a place on Virginia's Council. In 1751 he became lieutenant governor, exercising the colony's executive authority while its titled governors remained in Britain. His customs experience shaped his concern with revenue, royal prerogative and expansion.

His attempt to collect a pistole fee for signing land patents provoked a major dispute with the House of Burgesses. The assembly challenged the charge as arbitrary and sent Peyton Randolph to London to argue its case. A Privy Council compromise allowed some fees while exempting specified categories. At the same time, Dinwiddie sought to counter French advances into the Ohio country, where his public policy also intersected with his interest in the Ohio Company.

In 1753 he sent George Washington to demand the French withdrawal. When they refused, he supported an armed expedition in 1754; Washington's defeat at Fort Necessity helped open the wider imperial war. Dinwiddie welcomed Braddock's arrival in 1755, but the defeat on the Monongahela left Virginia's frontier exposed. He struggled to secure troops and money, and relations with both the assembly and Washington were often strained. He left Virginia in 1758 and retired to Britain. His governorship joined taxation and western land claims with imperial war.