He was born in Cagliari, Sardinia and entered the Society of Jesus, an order of the Roman Catholic Church, when he was fourteen years of age.
Congiato became the second president of two different Jesuit colleges in the San Francisco Bay Area.
His tenure in Santa Clara, (1856–1858), saw the construction of the first chapel, renovations of the theatre and gymnasium, and the establishment of the Philhistorian and Philalethic Debating Societies.
Afterwards, Congiato succeeded Anthony Maraschi as president of Saint Ignatius College in San Francisco in 1862, serving two separate terms and presiding over Saint Ignatius' expansion in downtown San Francisco.
For nearly twenty years he served as the pastor of St. Joseph's Church in San Jose, California and constructed the Jesuit Novitiate at Los Gatos, where he died in 1897.