In 1675, as Bishop of Lviv, he was also appointed administrator to the Diocese of Kyiv. In 1677, after contacts with the papal nuncio in Warsaw Yosyf Shumlyansky adopted Catholicism.
In 1675, he served as Bishop of Lviv and later became administrator of the Diocese of Kyiv.  In 1677, after meeting with the papal representative in Warsaw, Yosyf Shumlyansky embraced Catholicism.