First recorded as Marlebourough Street in 1715 on Maclanachan's plan of Belfast.
"The portion of the town from the foot of High Street extending in the direction of the river was mostly reclaimed by Isaac Macartney, who expressed his attachment to Whig principles by naming his quays and streets—George Quay, Hanover Quay, Marlborough Street, and Prince Street" (James O'Laverty, An Historical Account of the Diocese of Down and Connor, vol II, p. 398). Marlborough Street was named for the Duke of Marlborough, Queen Anne's victorious general. Macartney's development of the Brunswick Square area was a rare exception in this period (early 18th century) of a private merchant's development not under the aegis of the Donegalls (IHTA 12, p. 4).
Marlborough Street (Donegall Quay) is featured in Henderson’s 1850 edition of the Belfast Street Directory.
This is one of the earliest names in Belfast to commemorate someone not directly connected with the town's history.