The Diocese of Malolos is a Roman Catholic diocese located in the province of Bulacan, Philippines. Established on January 28, 2003, it serves as a spiritual and administrative region for the Catholic Church, overseeing various parishes and communities. The diocese is part of the ecclesiastical province of Manila and is dedicated to the pastoral care of its faithful. The diocese's patron saint is San Isidro Labrador, reflecting its agricultural heritage. The Cathedral-Basilica of the Immaculate Conception in Malolos City serves as the diocese's mother church. The diocese actively engages in various social and educational programs to support the local community.