Reus-Froylan was born on April 14, 1919, in Santurce, Puerto Rico, the son of the Reverend Esteban Reus-Garcia.
He also spent some time as rector of St Hilda's Church in Trujillo Alto, Puerto Rico.
In 1959 he became Dean of St John's Cathedral and rector of the Spanish speaking congregation.
David Andres Alvarez subsequently presided over the process to reunite the "Iglesia Episcopal Puertorriqueña" that Bishop Reus had created, as a diocese of the U.S. national church.
He was buried at the Episcopal cemetery at Barrio Limón in Ponce, Puerto Rico.