After the death of his father, Nicholas II, in 1316, it was decided to divide Werle.
took control over the part Werle-Goldberg and his uncle John II took over Werle-Güstrow.
Under the Peace of Brudersdorf, Pomerania was allowed to keep Rügen, but had to pay Mecklenburg 31000silver marks in compensation.
From 1350, he left the business of government to his son and co-ruler Nicholas IV.
They had three children: After Mechtild's death, John III married Richaris and had two more daughters: