The choice of our Marian patronage is traced to the early Carmelites first church on Mount Carmel, which was dedicated to her. The title of the Marian order was already in wide use by the middle of the 13th century.
In the Virgin Mary, mother of God and of the Church, the Carmelites find a perfect image of everything they desire and hope to be. This is why Mary has always been considered the patron of the Order.
Courtesy of OCarm.org