He was also titular Ban of Croatia and Dalmatia in 1419 and was a member of one of the most powerful Croatian noble families at the time.
At the peak of his power, he ruled areas in inner Croatia from the mountain of Velebit to the Cetina river.
Ivaniš was born before 1379 to Ivan II Nelipić and his wife Margarethe, who from the Split noble family Merini.
During the dynastic wars he was initially supportive of Ladislaus of Naples, from who he received Skradin and Klis.
According to his will, his daughter Princess Catherine Nelipić was to inherit all of his extensive possessions from the Velebit ranges to the Cetina river.