Bogislaw was born in Barth as a member of the House of Pomerania. He was the third son of Duke Bogislaw XIII by his first wife Clara of Brunswick-Lüneburg. On the death of his father in 1606, he and his younger brother George II became joint dukes of Rügenwalde (Darłowo). George II died in 1617, and Bogislaw became sole ruler. In 1620 his domain was incorporated into the Duchy of Stettin, which he inherited on the death of his elder brother Francis. Early in 1625 he became ruler of all West Pomerania on the death of the last Duke of Wolgast, Philipp Julius, and on 19 February he was married to Elisabeth (24 September 1580 – 21 December 1653), fifth daughter of John II, Duke of Schleswig-Holstein-Sonderburg, by his first wife, Elisabeth of Brunswick-Grubenhagen.