Kim Taegon was born in 1821 into a Catholic family in a Church that had been founded by Korean laymen, without missionaries, a generation earlier. His great-grandfather and his father both died for the faith. Chosen for the priesthood at fifteen, he was smuggled to Macau to study and ordained in Shanghai in August 1845, then returned by sea to a country where the faith was outlawed.
He was arrested in June 1846 while trying to open a route for missionaries along the coast and was beheaded at Saenamteo, on the Han River in Seoul, on September 16, 1846. He was twenty-five and had been a priest for thirteen months. Catholics recovered his body and buried it at Mirinae, south of Seoul, where a shrine stands today.
St. John Paul II canonized him on May 6, 1984, in Seoul, together with Paul Chong Hasang and 101 companion martyrs, at an open-air Mass at Yeouido. In 2023 a statue of him was placed in an exterior niche of St. Peter's Basilica. He is one of the five patrons of World Youth Day Seoul 2027.