He was the eldest son of Landgrave Louis II and his wife Judith of Hohenstaufen.

He stood initially on the side of Henry the Lion of the House of Welf.

In 1184 he was present when Henry VI held court at a Hoftag in the Petersberg Citadel in Erfurt, during which the floor collapsed and 60 attendees fell to their death in the latrine below (see Erfurt latrine disaster).

When the main army took the land route via the Balkans and Asia Minor, Louis III and his contingent embarked in Brindisi and sailed to Tyre.

However, before Barbarossa arrived with the main army, Louis III fell ill and decided to return home.