The Roman Catholic Diocese of San José in California is an ecclesiastical territory or diocese of the Roman Catholic Church in the northern California region of the United States. It comprises Santa Clara County, and is led by a bishop. Its patron saints are Saint Joseph and Saint Clare of Assisi. The diocese is a suffragan of the Archdiocese of San Francisco. Its fellow suffragans include the Dioceses of Honolulu, Las Vegas, Oakland, Reno, Sacramento, Salt Lake City, Santa Rosa and Stockton.
The Cathedral Basilica of St. Joseph in Downtown San Jose is the cathedral church of the diocese. The diocesan offices are located at 1150 North First Street. The diocese serves over 600,000 Catholics in 52 parishes and missions, three university campus ministries, and 38 schools.