Raynal was educated by the Jesuits and joined the order as a young man, but, after going to Paris to work for the church, he gave up religious life in favour of writing. He established himself as a writer with two historical works, one on the Netherlands (1747) and the other on the English Parliament (1748), both of them hackwork but popular and widely read. From 1750 to 1754 he edited the government-supported literary periodical Mercure de France, winning literary respectability and a place in society.

Raynal's most important work was the Histoire des deux Indes (History of the East and West Indies), a six-volume history of the European colonies in India and America. The first edition appeared in 1770, followed by several expanded versions. It denounced European cruelty to colonial peoples, which it blamed on religious intolerance and arbitrary authority. The philosopher and encyclopaedist Denis Diderot (Diderot, Denis) is credited with writing many of the better passages, as well as the more radical historical interpretations. The work was extremely popular, going through 30 editions between 1772 and 1789, its radical tone becoming more pronounced in the later editions.

In 1774 the History was placed on the Roman Catholic church's Index of Forbidden Books, and in 1781 the authorities ordered Raynal into exile and decreed that his history be burned. He was allowed to return to France, but not to Paris, in 1784. His banishment from Paris was finally rescinded in 1790.

Although he had been elected to the Estates-General in 1789, Raynal, from the early days of the Revolution, refused to serve, because he opposed violence. He later even renounced radicalism and prepared a message that was read to the National Assembly (successor to the Estates-General) in May 1791, calling for a constitutional monarchy modeled on the English system. His property was later confiscated by the National Assembly, and he died in poverty.