Gerlach VI of Isenburg-Limburg (died 1365), also known as Gerlach III of Limburg, was Count of Isenburg-Limburg and Lord of Limburg an der Lahn.
Gerlach VI of Isenburg-Limburg was the Count of Isenburg-Limburg from 1354 until 1365. After Gerlach's death in 1365, the line of counts of Isenburg-Limburg was extinct, so the Archbishops of Trier annexed Limburg an der Lahn.