During the war in Donbas he was the commander of the 2nd assault squadron "West" of the 24th Battalion of Territorial Defense "Aidar" of the Armed Forces of Ukraine, formed mainly from volunteers from Volyn Region.

From June 2014, he took part in the Anti Terrorist operation (ATO), and was elected as the commander of the 2nd assault squadron "West" of the 24th Battalion of Territorial Defense "Aidar" (military unit PP V 0624), which is subordinated to the Armed Forces of Ukraine.

Under his command, eight settlements were liberated in Luhansk Region, particularly Shchastia, Georgievka, Lutugino, Uspenska, Novosvitlivka and Khryaschuvate, and other strategically important objects.

After the 2014 Ukrainian parliamentary election, the People's deputy of Ukraine Ihor Lapin went to the zone of the ATO to help soldiers, shoving and teaching them skills and experience of conducting military operations.

Captain Ihor Lapin was back on the frontlines of the war since the outset of the full-scale Russian invasion of Ukraine, participating in combat operations near Hostomel Airport and Irpin, Kyiv region.

Also, Lapin and ROK’s coordinators formed the "Free Ukraine" volunteer battalion, which played a critical role in the defence of Kyiv.

In recognition of his outstanding service and dedication to the Ukrainian Armed Forces, Ihor Lapin was awarded the military rank of Major on May 6, 2022.

The Special Forces Battalion, under the leadership of Major Ihor Lapin, played a critical role in combat operations in eastern Ukraine.

Major Ihor Lapin suffered a severe injury during combat in the fall of 2022 and was subsequently dismissed from the Armed Forces of Ukraine.

Legislative cooperation with the parliament, the fight against the influence of clan-oligarchic structures on the state institutions of Ukraine and the popularization of preparations for repelling the Russian invasion are the main activities of Ihor Lapin until 02/24/2022.