[2] He was the thirteenth child and seventh son of John the Younger, Duke of Schleswig-Holstein-Sonderburg (1545–1622) and his first wife, Elisabeth of Brunswick-Grubenhagen (1550–1586).
[3] On the death of his brother Duke Christian of Schleswig-Holstein at Ærø in 1633, he inherited that island, as well as the town of Koping (Ærøskøbing), the district of Wuderup (Vodrup) and the domain of Gravenstein (Gråsten).
The Æero appanage remained hereditary in Philip's branch of the dynasty until being purchased by their kinsman Frederick V of Denmark in 1749, who dissolved it as a fideicommis in 1767.
Philip also purchased the domain of Freinwillen in Schleswig which he gave to his unmarried youngest (surviving) daughter Hedwig (1640-1671).
In 1648, Philipp bought, from Hans von Ahlefeld, another domain called Gravenstein located, however, in the Sundeved north of the Flensburg Fjord.