Varvakis was a Greek Orthodox Christian who became a skilful sailor at the age of 17 and built a ship, the St. Andrew, which he later offered (with his crew) to the Russian forces during the Russo-Turkish War, 1768-1774.

He spent his entire fortune to equip the ship and to arm it with cannons and showed extraordinary courage during the Battle of Chesma (Turkish: Çeşme) in July 1770.

But the war did not give independence to Greece, as the Ottoman sultan signed peace by the Treaty of Kuçuk Kainarji in 1774, which granted Russia the northern part of the Black Sea.

He went to Saint Petersburg, where he met with Grigori Alexandrovich Potemkin, Russian general-field marshal, statesman, and favorite of Catherine II the Great, who arranged the audience with the Empress of Russia.

Catherine II the Great was particularly generous giving Varvakis 1,000 golden roubles as a gift and an authorisation for unlimited and duty-free fishery in the Caspian Sea and the right to choose a place to settle in Russia.

In 1810-17, Ioannis Varvakis financed the delayed construction of the channel linking the Volga to its arm Kutum [ru].

In 1813, Ivan Varvatsi spent 600,000 rubles for construction of Greek Jerusalem Monastery (Иерусалимский греческий монастырь) in Taganrog.

After the destruction of the island by the Turkish Fleet, he returned to Greece himself in 1824 to aid the refugees, and died on Zakynthos on January 10, 1825.

Varvakis desired to promote education for the new Greek state, and in his will he left 1 million rubles for the building of a high school, which was named Varvakeio (Βαρβάκειον Λύκειον) in his honor.

All sons of Maria and Nikolay Komnino-Varvatsi (Ivan, Yegor, Mark, Kozma and Andrey) were granted noble titles by the Yekaterinoslav Government decree of April 25, 1821, paying tribute to achievements and contributions made by their grandfather, Ioannis Varvakis.