In 1948, with encouragement from the German pastor at St. George, Bloomington, a building committee of six started work on establishing a Catholic Church in Rialto. The team collected enough funds to convince Bishop Charles Buddy of San Diego to establish the parish the next year. A German priest, Fr. Albert Swartz, was named the first pastor. He chose to name the church St. Catherine of Siena after Catherine Moffatt, the elderly parishioner who was the first Altar Society President. 

The complex consisted of the church and a one-bedroom rectory with a garage and hall between. In 1958 the church was enlarged to twice its original size to accommodate the growing parish community. Two years earlier saw the opening of St. Catherine School. The sisters staffing the school received a convent, which was blessed by Bishop Furey in 1966. 

Fr. Robert Miller, pastor from 1980, initiated Renewal Weekends that touched the lives of many and led to St. Catherine becoming an active and leading church in the community. When the church burned down on January 5, 1985, the present church and office buildings were erected and blessed by Bishop Phillip Straling on February 8, 1992.