Czartoryski was chosen by his family to be a priest from the early childhood, receiving the title of canon when he was 13 years old.

Starting that year, the influence of familia resulted in him receiving a series of prosperous prebendaries, as well as becoming one of the ecclesiastical judges in the Crown Tribunal.

In 1756 he spent a good part of the year traveling around his diocese, supporting the rebuilding of the town of Krobie which recently suffered a major fire.

In the 1750s he also sponsored the reconstruction of the Archcathedral Basilica of St. Peter and St. Paul, Poznań, as well as the bishop's palace in Ostrów Tumski.

Unlike many of the contemporary magnates, Czartoryski's lifestyle was relatively modest, and he preferred his smaller palace in Dolsk to the lavish residence of Poznań's bishop in Ciążeń.

Familia decided to support the candidate, Stanisław August Poniatowski, but other Polish neighbours also tried to influence the beginning of the royal election.