[1] Gerhard was the third son of Dietrich of Oldenburg and his wife, Hedvig of Holstein.

His eldest brother first succeeded their father and later was elected King Christian I of Denmark in 1448, therefore passing on the county to his brothers in 1450.

From 1440 to 1463 Gerhard VI ruled in Delmenhorst as regent and from 1464 to 1482 (after the death of his brother Maurice) as the guardian of his nephew Jakob.

He was constantly at war with Gerhard III, Prince-Archbishop of Bremen, and Frisians.

In 1483 Gerhard was compelled to abdicate in favor of his sons, and he died whilst on a pilgrimage in the Rhône valley.