He was the eldest son of Bernard III and his wife, Sofie of Cuijck-Arnsberg.
With his uncle, Bishop Simon I of Paderborn, he fought in the Battle of Zülpich of 1267 against the Duchy of Jülich.
In 1269, Bernard IV paid a large ransom to secure Simon's release.
He had to borrow the money, causing the House of Lippe to be burdened by debt.
[1] In 1260, Bernard married Agnes (c. 1232 – c. 1 August 1285), a daughter of Count Dietrich V of Cleves and Hedwig of Meißen.