From 1048 until 1552 (de jure until 1648), it was also a state of the Holy Roman Empire.

In 550 AD, the Frankish Council of Toul was held in the city.

By the high Middle Ages, the diocese was located at the western edge of the Holy Roman Empire; it was bordered by France, the Duchy of Bar, and the Duchy of Lorraine.

In 1777 and 1778, territory was carved out of Toul to form two new dioceses: Saint Dié and Nancy, both of them suffragans of Trier.

The geographic remit included three Departments of France: Meurthe, Meuse, and Vosges.