St. Joseph Co-Cathedral is a Catholic cathedral located in Thibodaux, Louisiana, United States. Along with the Cathedral of St. Francis de Sales in Houma it is the seat of the Diocese of Houma-Thibodaux. It is also the oldest parish in the diocese. The church building and rectory were listed on the National Register of Historic Places as Saint Joseph's Co-Cathedral and Rectory on March 5, 1986 as part of the "Thibodaux Multiple Resource Area".