One son perished in Siberia, likely sent there by Czar Alexis of Russia, while the other (likely Yurii) escaped to Voloshchyna and then to Bukovina (modern-day the Chernivtsi region) before 1647.

In response to Polish-Lithuanian encroachments, Nechai participated in the Khmelnytsky Uprising that sought to secure independent Cossack rule over Ukraine.

Nechai participated in the campaign of the Cossack army in Galicia, where on behalf of Khmelnytsky they seized the Brody Castle and, together with other commanders, besieged Lviv, and stormed Zamość.

In the winter of 1649 Nechai led negotiations with Polish representatives in Kyiv and Pereyaslav, and in the following year he was honoured for his role in the Zbarazh and in the Battle of Zboriv.

During Khmelnytskyi's invasion of Moldavia, together with Matviy Gladky Nechai took Soroca, and in September 1650 captured the Moldavian capital of Iaşi, forcing its ruler Vasile Lupu to agree to an alliance with Tymish Khmelnytsky.

While celebrating Shrovetide, he was ambushed and died in a battle with numerically superior Polish forces led by field hetman Marcin Kalinowski, who captured Nechai's coat of arms.

Local lore purports that the hill on the grave was built by Nechai's loyal troops, with each Cossack carrying a hatful of soil to the site.

According to a different version, the Poles cut up Nechai's body and scattered it: presumably it was gathered by his loyal forces, and then buried or possibly carried to Kyiv (either in part or together) or elsewhere.

Considered to be second only to Khmelnytsky, he is a hero of the fight for Ukrainian independence and is honored to this day by an annual procession to his burial mound (mohyla) on the date of his death.