Robert Boyd was the only son and heir by second wife of Robert Boyd, 7th Lord Boyd. He was made Justice of the Peace for Cuningham on 25 November 1634. On 22 February 1638 he was one of the noblemen who ascended the mercat cross in Edinburgh to protest against the proclamation made that day, which contained the royal approbation of the service-book
He subsequently subscribed the National Covenant, when renewed March the following, in the kirkyard of Greyfriars Kirk, and actively co-operated with the Covenanters in their opposition to King Charles.
He was present in Parliament 31 August 1639 and 2 June 1640. He died of a fever on 17 November 1640.
Robert Boyd was the only son and heir by second wife of Robert Boyd, 7th Lord Boyd.