Originally, Saint-Simon was part of the territory between the Seigneurie des Trois-Pistoles and the lands of Bic belonging to Monsieur de la Chenaye. In 1751, Nicolas Rioux, Lord of Trois-Pistoles, was granted these lands by the Marquis de Jonquière, governor, and Mr. François Bigot, intendant of New France. Thus was born the Seigneurie Nicolas Rioux, sometimes spelled Nicolas-Riou.

In 1792, a wealthy merchant, Jean Drapeau, bought this seigneury. It was the latter who opened up this vast expanse of land to colonization. In 1796, the first settler, Régis Jean, arrived from Saint-Jean-Port-Joli. Subsequently, at the beginning of the 19th century, people from Trois-Pistoles settled there. Around 1828, there were 1,125 people divided into 150 families in the territory which then included five ranks. In 1858, there were 1,800 inhabitants.