He departed for East Asia on 6 February 1844, intending to serve as a missionary in the Ryukyu Islands of Japan.

[citation needed] He arrived in Macau, where he was persuaded by the newly appointed apostolic vicar of Korea, Jean-Joseph-Jean-Baptiste Ferréol, to accompany him there instead.

With the assistance of Hwang Sŏk-tu, he wrote A Brief Record of Reflection and First Journey in Divine Life, published in Woodblock print.

He was beheaded at a Korean naval base in Galmaemot (갈매못) near present-day Boryeong along with two French priests, Pierre Aumaître and Martin-Luc Huin, and two lay catechists, Lucas Hwang Sŏk-tu (Bishop Daveluy's personal assistant) and Joseph Chang Chu-gi.

[citation needed] The deaths of Berneux, Daveluy and other Catholic missionaries in Korea was followed by a French punitive expedition which reinforced the Korean policy of isolationism.