Educated at the University of Oxford, he entered the army in 1712 and joined the Austrian army fighting the Turks in 1717. On his return to England in 1722, he entered Parliament. In 1729 he presided over a committee that brought about prison reforms. This experience gave him the idea of founding a new colony in North America as a place where the poor and destitute could start afresh and where persecuted Protestant sects could find refuge.

In 1732 Oglethorpe secured a charter for his colony in what became Georgia. In 1733 he accompanied the first settlers and founded Savannah. On the outbreak of the war between England and Spain in 1739, he led a vigorous defense of the territory. He was foiled in an attempt to capture the Spanish town of St. Augustine, Fla., but was able to repel an attack on Fort Frederica, Georgia (1742). Oglethorpe's popularity, not only with his hurriedly raised and imperfectly trained troops but also with all classes of the population, helped to assure the safety of the colony.

Oglethorpe returned to England in 1743, where he resumed his parliamentary career.