It was located in an area corresponding generally to the present-day northeastern Mexican state of Nuevo León.

Philip granted Luis de Carabajal y Cueva the title of first governor and captain-general of this new province in New Spain.

The foundation of this realm was a crucial event which potentially helped the subsequent Spanish settlements in Texas.

Though the New Kingdom of León was part of the Viceroyalty of New Spain, it remained functionally autonomous during much of its history, due to the long distance between its main cities; however, it quickly developed a shared culture with its neighbor provinces.

This fact led to its becoming in 1776 part of the semi-autonomous Commandancy General of the Provincias Internas, which split in 1786 into three commands, one of them being the Eastern Internal Provinces (Provincias Internas de Oriente) consisting of the New Kingdom of León and the provinces of Coahuila, Tejas, and Nuevo Santander; subsequently it remained part of the comandancy until 1821 when it and the rest of Mexico became an independent republic.