[1] Its foundation was confirmed by the Sejm of the Polish–Lithuanian Commonwealth in 1618, however the first bishop Piotr Parczewski was appointed only in 1636.

Initially, the territory of the diocese formed part of the Polish–Lithuanian Commonwealth, however, after the Truce of Andrusovo of 1667 it passed to Russia.

On 15 April 1783, it lost all of its territory due to the establishment of the Metropolitan Archdiocese of Mohilev (but having still a chapel and temporalities in Warsaw until 1807-1809).

[2] In 1818, it was formally suppressed and its territory canonically merged into the Metropolitan Archdiocese of Mohilev, which would be merged in 1991 with the Diocese of Minsk into the Metropolitan Archdiocese of Minsk-Mohilev at the dismemberment of the Soviet Union, so as to cover independent Belarus.

The Catholics in Smolensk are now part of the parish of the Immaculate Conception Church in the Archdiocese of the Mother of God in Moscow.