The Catholic Diocese oversees the western metropolitan region surrounding Incheon.

Catholic ministry in the Incheon area began when the region was incorporated into the Apostolic Vicariate of Seoul on 1 September 1958,and designated as the Incheon Vicariate Forane. Pastoral care was entrusted to the Maryknoll Fathers and Brothers (Catholic Foreign Mission Society of America).

On 6 June 1961,the Incheon region was fully separated from the Seoul Vicariate and established as the Apostolic Vicariate of Incheon, with Bishop William McNaughton (Na Gil-mo) of the Maryknoll Society appointed as the first Vicar Apostolic. On 10March 1962, when the Holy See formally established thehierarchical structure of the Church in Korea, the Apostolic Vicariate of Incheon was elevated to the Diocese of Incheon.

At its founding, the diocese consisted of fiveparishes established before the Maryknoll mission began in October 1958—Dapdong, Songnim-dong, Bupyeong(now Bupyeong 2-dong), Gimpo, and Ganghwa—and four additional parishes established by the Maryknoll missionaries: Dohwa-dong, Seonrin-dong(now Haean), Yeonpyeong Island, and Baengnyeong Island, making a total of nine parishes.

Following the elevation to diocesan status, pastoral and institutional development advanced rapidly under the leadership of the first bishop, Bishop William McNaughton, who oversaw the establishment and growth of parishes, organizations, and diocesan institutions. On 27 December 1999, the second bishop, Boniface Choi Ki-san, laid the foundation for the stabilization of the diocese, and under this foundation, John the Baptist Cheong Shin-chul was appointed the third Bishop of Incheon on 10 November 2016.

As of 31 December 2023,the Diocese of Incheon encompasses Incheon Metropolitan City, and parts of Bucheon, Gimpo, Siheung, and Ansan in Gyeonggi Province—covering one metropolitan city and four cities (two partially). The diocese comprises 134parishes, 28 mission stations, 1bishop, 356 priests, and approximately 520,000 faithful.