In 1248, King Louis and Queen Margaret traveled to Egypt to participate in the Seventh Crusade.

He did not actually rule the country; real power was in the hands of a royal council, led by his uncles Alphonse and Charles.

The legal scholar Pierre de Fontaines dedicated his textbook Conseil à un ami to Prince Louis.

Louis and his younger brother Philip witnessed the sealing and oaths confirming the 1259 Treaty of Paris, which was intended to end the territorial conflict between England and France that had been raging since 1180.

The theologian Vincent of Beauvais wrote a consolatio for Louis IX, which is considered the traditional Christian consolation and a masterpiece in its genre.