Having formed an alliance with the Republic of Venice, he led the Serb resistance against the expanding Ottoman Empire[1] He was successful at first but lost his realm in 1479.

In his youth Ivan took part in the raids against the domains of Stefan Vukčić Kosača, the duke of Saint Sava in Hum,[5] and on one occasion (between 1442 and 1444)[6] he was captured.

[7] Venice saw Stefan Crnojević as an important potential ally in their war against Serbian Despotate, so they tried to bring him closer by accepting his request to maintain a pressure on Kosača to release Ivan.

[8] Stefan was ready to do anything to have Ivan released from Kosača's captivity, so he complied with Venetian condition to allow them to suppress the rebellion in Grbalj.

After Venetians brutally suppressed the rebellion in Grbalj they forced Kosača to reluctantly release Ivan to them and spent 120 ducats to buy him new clothes before handling him to his father.

But thanks to moves of the Stefan Vukčić and Skanderbeg,[11] in 1466 he became a duke under payment from the Venetian Republic with the capital in Žabljak at Lake Skadar.

In 1477 Ottomans captured most of the territory of Zeta together with Žabljak and defeated main army of Ivan Crnojević late in 1477 or early 1478.

That way Venice sacrificed its ally Ivan Crnojević who was not included into the peace treaty and had to leave his Zeta and find a haven in Italy.

Wishing to preserve the realm of Zeta and its independence from the Ottomans because he didn't feel safe at the edge and the border, Ivan moved its capital deeper into the hills to a more easily defended location in the field of Cetinje at the foot of Mount Lovćen.

Ivan brought a range of legislative acts that were later of great importance for the legal and cultural history of a future Montenegro.

His youngest son Stanko converted to Islam and received the name Skender, hence he is also known as Skenderbeg Crnojević, and became the Ottoman sanjakbey of the Sanjak of Montenegro when it was established in 1514.

То је било веома значајно, јер велика млетачка флота није могла да се пробија дал.е од Светог СрђаУз помоћ Дубровчана људи Ивана Црнојевића су крстарили језером и ноћу нападали турске шаторе.