Father Tarnacki was born in Poland and immigrated to the United States with his family at the age of 12. He grew up in Stamford, Connecticut, and, after graduating from high school in 2008, joined the Pauline Fathers, beginning his religious life. He studied at the Pauline Seminary at Skałka and at the Pontifical University of John Paul II in Kraków. He earned a master’s degree in theology and was ordained a priest in 2016 at the National Shrine of Our Lady of Czestochowa in Doylestown, where he began his ministry. He is particularly involved in ministry to youth and young adults, serving as a co-founder of the Częstochowa Young Adults (CYA) group and as a chaplain and theology teacher for the homeschooling community.