Duke Philip Sigismund of Brunswick-Wolfenbüttel (July 1, 1568 in Hessen am Fallstein – 19 March 1623 in Iburg) was a Lutheran administrator of the Prince-Bishopric of Verden and Osnabrück (1591–1623) son of Julius, Duke of Brunswick and Lunenburg, Prince of Wolfenbüttel and Hedwig of Brandenburg.