The Diocese of Tarnów () is a Latin diocese of the Catholic Church in Poland. According to Church statistics, it is the most religious diocese in Poland, with 72.5% weekly Mass attendance.
The latest statistics, published in December 2025, showed the diocese has the highest rate of Sunday Massgoers in the country (62.3%), well ahead of the next highest dioceses of Rzeszów (52.4%) and Przemyà Âl (50.0%).