Theodoric was the second son of Henry the Illustrious, margrave of Meissen and Lusatia, and his wife Constance of Babenberg, a daughter of Duke Leopold VI of Austria.
In 1261, his father split the Margraviate of Landsberg off from his Lusatian territory, which after the War of the Thuringian Succession in 1265 he transferred to Theodoric, thereby creating a cadet branch of the Wettin dynasty.
The territory comprised the westernmost part of Lusatia between the Saale and Mulde rivers, centered around Landsberg Castle.
Theoderic's march included the towns of Delitzsch, Leipzig and Groitzsch, his estates stretched down to Zwickau and Grimma with the residence at Weißenfels.
Theodoric died in 1285 on the way back from Silesia, where he had betrothed his daughter Gertrude to the Piast duke Bolko I the Strict.