He was born in Kötzlin, Altmark. After serving as a page on the court of Prince Frederick Ulrich of Wolfenbüttel, he entered Imperial military service in 1620. After the dissolution of Wallenstein's troops and Gustavus Adolphus' intervention, Königsmarck offered his services to the Swedish King. By 1635 he commanded his own regiment. He was appointed major general in 1640, governor general of Bremen-Verden in 1645, Privy Councilor in 1651 and field marshal in 1655. He is best known for the Siege of Prague between 25 June and 1 November 1648, where he managed to capture and loot the left-bank part of Prague but failed to take the Old Town until fighting ended with news of the Peace of Westphalia.