Petersburg was formed from parts of Dinwiddie, Prince George, and Chesterfield Counties. A garrison and fur trading post called Fort Henry was established there in 1645 on the site of the Indian town Appamattuck. The present name, suggested in 1733 by William Byrd (1674-1744), honors Peter Jones, Byrd's companion on expeditions into the Virginia backcountry. Petersburg was established in 1748 and incorporated as a town in 1784. In the latter year the towns of Blandford, Pocahontas, and Ravenscroft were added to Petersburg. It was incorporated as a city in 1850.

In 1780 the Virginia General Assembly replaced the Anglican vestries and churchwardens of the colonial period with elected bodies called Overseers of the Poor. The Overseers provided food, clothing, shelter, and medical treatment for the persons who were too poor to support themselves or too ill to provide for their basic needs. They also bound out children whose parents could not support them or who failed to educate or instruct them, as well as orphans to become apprentices. The boys learned a trade and the girls learned domestic skills.