He was associated with his father as prince of Salerno in 943 and he succeeded him on his death in 952. He took to using the title Langobardorum gentis princeps: "prince of the people of the Lombards." He was originally under the regency of his mother and Prisco (Priscus), treasurer (comes tesaurarium) and count of the palace (magister palatii).
In the next year, he allied with Landulf and besieged Neapolitan Nola. In October 953, he issued a diploma favouring the bishop of Naples, but the unscrupulous diplomacy of his neighbours never seemed to favour him. Sometime after 955, however, he was made a patrician by Marianus Argyrus, the Byzantine strategos of Bari.
The pope and Gisulf made a treaty at Terracina.
lieutenant was this act which bought him later assistance from the powerful Ironhead. His neighbour, the prince of Benevento and Capua, Pandulf Ironhead, restored Gisulf as his vassal.
Though Gisulf was married to Gemma, he died heirless in late 977 (or perhaps 978) and Pandulf succeeded in Salerno.
