The Margraviate of Landsberg (German: Mark Landsberg) was a march of the Holy Roman Empire that existed from the 13th to the 14th century under the rule of the Wettin dynasty. It was named after Landsberg Castle in present-day Saxony-Anhalt.
Upon the death of Margrave Conrad in 1156, the Wettin domains of Meissen and Lusatia were re-arranged. Conrad's younger son Margrave Theodoric I of Lusatia had Landsberg Castle erected until 1174 and began to style himself a "Margrave of Landsberg".
However, an Imperial State in its own right was not established until in 1261, when Margrave Henry the Illustrious (against legal provisions) split off the western Landsberg territory from the March of Lusatia as a separate margraviate for his second son Theodoric. After Dietrich's son Frederick Tuta had died without male heirs in 1291, his uncle Margrave Albert II of Meissen sold it to the Ascanian margrave Otto IV of Brandenburg.
In 1327 the Welf duke Magnus I of Brunswick-Lüneburg inherited Landsberg by marrying Sophia of Brandenburg-Stendal, the sister of the last Ascanian margrave Henry II and also the niece of the German king Louis IV, who had seized the Brandenburg possessions in 1320. Duke Magnus sold Landsberg to Margrave Frederick II of Meissen in 1347, and in this way the former margraviate finally fell back to the House of Wettin.