Giso IV married Kunigunde, the daughter of Count Rugger II of Bilstein.
Giso IV acquired considerable possessions and bailiwicks via her, mostly in the Werra area, the Upper Lahngau and on the Rhine — among these were the advocatus positions over Hersfeld Abbey and the St. Florins church in Koblenz.
Between 1115 and 1118, they recognized the Archbishop Adalbert of Mainz, an avowed opponent of the Emperor in the Investiture Controversy, as liege lord for all of their formerly imperial fiefs in Upper and Lower Hesse, including Hollende Castle, the ancestral seat of the Gisones.
This brought Mainz considerably closer to its aim of dominating a large, contiguous territory in Hesse.
It is unclear whether Giso inherited the counties of Maden and Gudensberg and the office of Imperial Standard Bearer because of his marriage with Kunigunde, or for some other reason.