Defender of Ukraine Day is a state holiday in Ukraine celebrated annually on 14 October.

Its first celebration was in 2015. Starting from 2015, this day is considered a public holiday. It is a day off for the general population, and schools and most businesses are closed. The day honors the courage and heroism of defenders of Ukraine’s independence and territorial integrity, military traditions and feats of the people of Ukraine.

October 14 is the day of the Intercession of the Theotokos. It was the Ukrainian historical tradition to honor the Ukrainian Army on this day. This holiday has been celebrated by Ukrainians since the 12th century. The holiday was especially popular among Ukrainian Cossacks, who celebrated it since at least the 17th century as they believed theMother of God (also known as Theotokos) to be their patroness. 14 October is also the Day of the Ukrainian Cossacks.

In an effort to adopt some Cossack traditions, the Ukrainian Insurgent Army chose the day of the Intercession of the Theotokos to be the official day of their establishment.

In the Ukrainian tradition going back to the medieval times of the Kyiv Rus, the  Intercession of the Virgin Mary is interpreted as a symbolical act of protecting and blessing the Ukrainian people.