The Diocese of Bielsko–Żywiec (Latin: Dioecesis Bielscensis-Zyviecensis) is a Latin diocese of the Catholic Church located in the cities of Bielsko and Żywiec in the ecclesiastical province of Kraków in Poland.
It was established as the Diocese of Bielsko–Żywiec from the Diocese of Katowice and Metropolitan Archdiocese of Kraków on 25 March 1992. In 2013 about a half of the then Catholic Church members attended church services at least once per week.
Bielsko-Biała (Polish: [ˈbjɛlskɔ ˈbjawa] ; Czech: Bílsko-Bělá; German: Bielitz-Biala), is a city in the Silesian Voivodeship, southern Poland, with a population of approximately 166,765 as of December 2022, making it the 22nd largest city in Poland, and an area of 124.51 km (48.07 sq mi). It is the core of the broader metropolitan area with around 335,000 inhabitants. It serves as the seat of the Bielsko County, Euroregion Beskydy, Roman Catholic Diocese of Bielsko–Żywiec and the Evangelical Church Diocese of Cieszyn.
Situated north of the Beskid Mountains, Bielsko-Biała is composed of two former towns which merged in 1951—Bielsko in the west and Biała in the east—on opposite banks of the Biała River that divides the historical regions of Silesia and Lesser Poland. The history of Bielsko dates back to the 13th century, while Biała was founded in the 16th century and obtained city rights in 1723. Despite the administrative separation, both towns effectively functioned as one urban area already in the 19th century. Industrialization, especially the textile and automotive industries, was of great importance for its development in the past. Between 1975 and 1998, the city was the seat of Bielsko-Biała Voivodeship and currently lies within the Silesian Voivodeship.