He was born in Prague to Ferdinand August Leopold, 3rd Prince of Lobkowicz and Duke of Sagan, and his second wife, Marie Anna Wilhelmine von Baden-Baden and Hochberg. In his adult age he fought under Prince Eugene of Savoy against the French in the War of the Spanish Succession and later against the Turks during the Austro-Turkish War of 1716–1718. He succeeded Piccolomini after his death in Prishtina, Kosovo, but Johann increased taxes and failed to maintaining good relations and the Albanian and Serb forces went joined the Ottomans.