The first St. Josaphat Ukrainian Catholic Church was built on this site in 1904 by the Basilians and dedicated that year on the 27th of November, the Feast of St. Josaphat. It was a small, woodframe building with a cruciform plan, a single entrance, and a single large dome. By 1913, St. Josaphat's was too small, and renovations were carried out which doubled the size of the church. Despite these efforts, the church was again too small by 1938, and it was decided that an entirely new building was needed.
Construction on the new St. Josaphat church was begun in 1939 according to plans by Reverend Phillip Ruh. Ironically, Reverend Ruh was neither of Ukrainian origin nor a Basilian. Rather, he was a Belgian Oblate who had transferred to the Byzantine rite. Completed in 1944, the church was designated a cathedral in 1948 when Edmonton was made the seat of a newly-formed Ukrainian Catholic Exarchate. Although St. Josaphat's cost about $250,000 to build, only $150,000 was actually spent, the rest being contributed in the form of volunteer time and labour.
St. Josaphat's is the only example in Alberta of Reverend Ruh's "Prairie Cathedrals." Built following a cruciform plan, the Cathedral has seven cupolas and an
entrance portico supported by eight modified Tuscan columns. The proportions of the church do not emphasize the vertical to the extent originally envisioned by Ruh because the large interior space created would have been excessively costly to heat and because the cupolas crowning the church would have interfered with the flight-path of planes landing at the Municipal Airport. Extensive murals decorate the barrel vault and dome inside the church. Professor J. Bucmaniuk undertook the decoration of the church between 1950 and 1955. He included a scene of the Last Judgment, which depicts Stalin and Hitler among the damned and he and his mother among those ascending to heaven.
The Baroque effect achieved by the rich decoration of the interior, which was enhanced in 1968 by the addition of an elaborate iconostasis, and the exterior scheme of the architectural design undoubtedly created the effect desired by Reverend Ruh. St. Josaphat's Ukrainian Catholic Cathedral was one of Ruh's last large-scale churches. It remains essentially unchanged and was declared a Provincial Historic Resource in 1983.