His early years were partly spent at the court of his grandfather, Charlemagne, whose special affection he is said to have won. When the emperor Louis divided his dominions between his sons in 817, Louis received Bavaria and the neighbouring lands.

He may truly be called the founder of the German kingdom, though his attempts to maintain the unity of the Empire proved futile. Having in 842 crushed a rising in Saxony, he compelled the Obotrites to own his authority, and undertook campaigns against the Bohemians, the Moravians and other tribes, but was not very successful in freeing his shores from the ravages of Danish pirates.

Louis was preparing for war when he died on August 28, 876 at Frankfurt. He was buried at the abbey of Lorsch, leaving three sons and three daughters. His sons, unusually for the times, respected the division made a decade earlier and each contented himself with his own kingdom. Louis is considered by many to be the most competent of the descendants of Charlemagne. He obtained for his kingdom a certain degree of security in face of the attacks of Normans, Hungarians, Moravians and others. He lived in close alliance with the Church, to which he was very generous, and entered eagerly into schemes for the conversion of his heathen neighbours.