With a land area of 5,565 square kilometers, the Suwon Diocesan territory includes cities such as Ansan (part), Anseong, Anyang, Gunpo, Gwacheon, Gwangju, Gwangmyeong, Hanam, Hwaseong, Icheon, Osan, Pyeongtaek, Seongnam, Siheung (part), Suwon, Uiwang, Yongin, and counties such as Yangpyeong and Yeoju in the southern Gyeonggi-do province.
Suwon diocese was carved out from Seoul archdiocese on Oct. 7, 1963 as a suffragan diocese of Seoul Metropolitan. At that time, it had only 24 parishes and about 42,500 Catholics including 28 priests. By the end of 2004, it had 163 parishes and 662,614 Catholics, becoming the second largest diocese in Korea in terms of Catholic population.
Suwon diocese has many holy shrines. These include Chonjinam, the birthplace of the Korean Catholic Church, and the Mirinae Holy Shrine, where the tomb of the first Korean priest-martyr, Saint Priest Andrew Kim Tae-gon, is located, and which takes pride of place as the cradle of the Korean Catholic Church.
Suwon, the capital city of Gyeonggi-do, is famous for its Hwaseong Fortress, one of the renowned World Heritages designated by the United Nations Educational Scientific, and Cultural Organization (UNESCO). Suwon diocese covers the metropolitan areas surrounding Seoul. New cities and towns are being built and the population is growing rapidly.
At the end of 2017, the population in Suwon diocese stood at 8,133,304 (some 13.5 percent of the country's population of 51 million). Most residents are ethnic Koreans.
Standard Korean is in use. English, a mandatory subject in schools, can be spoken and understood in business and tourist areas. All traffic signs are in Korean and English.
Suwon diocese lies in the temperate zone, and has four distinctive seasons of spring, summer, autumn and winter. The yearly average temperature is 12.3 degrees Celsius. The annual precipitation in the region averages 1,328 millimeters. Most of the rainfall is concentrated in the rainy months (monsoon period) of June through September.
The southern Gyeonggi-do province is located in the middle of the Korean peninsula and is the center of South Korea's high-tech industry. The province's eastern region is mostly mountainous and and the western region is mainly plains.