Johnson was born c. 1676, in England, the son of Sir Nathaniel Johnson and Joanna Overton. Young Johnson spent part of his youth in the Leeward Islands, where his father served as governor from 1686 to 1689. The elder Johnson acquired large landholdings in South Carolina and moved there to develop his property and later served as governor of the province from 1702 until 1708.
Johnson first appeared in Carolina history in 1701, when he was accepted by the Board of Trade as surety for his father, who served in that capacity from 1702 to 1708. The son, a mercer, took oath as freeman of Newcastle-upon-Tyne, January 19, 1702/3. In 1713 the Carolina proprietors expressed an intention of appointing him to succeed Governor Craven. In 1715 Johnson appeared with others before the Board of Trade to request in vain that the Crown aid in defending Carolina against the Yemassee Indians. The proprietors likewise failed to help, and the settlers had to carry on their struggle alone, but finally succeeded in turning back the Indians.
Johnson was made governor in 1717, at a time when the colonists were petitioning that Carolina be made a royal province and rebellion against the proprietors was threatening. He arrived at Charleston to find the colony's coasts pillaged by pirates. After vain appeals to the proprietors for help, the colonists had sent out an expedition under Colonel Rhett, which defeated and captured the notorious Stede Bonnet, who later escaped and took part in pirate raids on Charleston harbor. Johnson, acting with courage and decision, organized a second expedition and in a pitched battle exterminated the buccaneers, recapturing Bonnet, who was sent to Charleston and hanged with twenty-two other pirate prisoners. Johnson's period as governor ended in 1719 when dissatisfaction with the weak and inefficient management of the proprietors reached a climax. The rebellion was immediately caused by the proprietors' disallowance of certain popular laws, including the regulation of elections to the legislature. Johnson's popularity was attested by the request of the revolutionary convention that he continue as governor in the King's name, an offer which he refused, remaining loyal to the proprietors. The revolutionists thereupon elected another governor and ultimately gained their ends when in 1729 a royal government was established in the colony, which was divided into two provinces, North and South Carolina. Johnson in the meantime had gone to England.
His efficiency and popularity were again recognized when he was selected as the first governor of South Carolina under the Crown, a position which he assumed in 1731. One of his instructions required fixing the line between his province and North Carolina, but this he did not accomplish. In 1732 he aided Governor Oglethorpe in founding the colony of Georgia, furnishing food and escort to the settlers. To safeguard the borders of his own province, he advocated further settlement through the erection of townships in which land would be granted to every actual settler, and also urged the giving of presents to the Indians and the stationing of an independent company on the frontier to maintain peace. He tried to promote his colony's growth by asking the Crown to help the Swiss and other foreigners emigrating there, and he welcomed Pierre Purry and his Swiss followers when they came to the lower Savannah and settled Purrysburg, which unfortunately did not prosper.
Johnson ultimately disposed of all his property in England and thoroughly identified himself with colonial life. His will shows that at the time of his death, which occured on May 3, 1735, he was a man of some wealth.
Johnson’s greatest overall contribution was his success in restoring social and political harmony during a volatile period in South Carolina’s history. As royal governor Johnson left an indelible mark on South Carolina history. In addition to his role in the development of Georgia as a buffer to Spanish Florida, Johnson implemented his visionary township system of settlement in South Carolina. With support from British officials and the assembly, Johnson’s township system was by all standards a resounding success. By 1735 nine townships had been surveyed and hundreds of Irish, Swiss, German, and Welsh settlers had immigrated into six of them. The Assembly erected a monument to him in Saint Philip's Church.
The esteem and respect in which Johnson was held are indicated by his title of "good Governor Robert Johnson. "
Johnson was married to a woman, named Margaret, who died in 1732. It is also known that he was the father of three sons and two daughters. His daughter Margaret married Henry Izard and became the mother of Ralph Izard.
