The following counts ruled over Holstein-Plön: Following the death of Gerhard II his sons, Gerhard IV of Holstein-Plön and his younger half-brother John III, ruled jointly over Holstein-Plön.

In 1314 Gerhard IV sold his lands to John III, who thus became the sole Count of Holstein-Plön.

Holstein-Plön reverted to Holstein-Kiel in 1350 upon the death of 27-year-old Gerhard V without issue.

When the Plön line died out in 1390, Holstein-Kiel (and Holstein-Plön within it) reverted to Holstein-Rendsburg, ruled by Count Nicholas of Holstein-Rendsburg (died 1397) and his nephew, Count Gerhard VI of Holstein-Rendsburg (died 1404).

A circa-1400 map of the region shows the borders of Holstein-Rendsburg and its subordinate counties, Holstein-Kiel and Holstein-Plön.