The patron saints of Olgiate Comasco are Saints Hippolytus and Cassian, celebrated on 13 August in the Church of Santi Ippolito e Cassiano.
The devotion of Olgiate's people to Saint Gerard of the Dyers, begun with a vow made in 1207, still continues today with a pilgrimage to his tomb in Monza every 25 April. The town also holds the Church of San Gerardo and the Church of the Visitation of the Blessed Virgin Mary at Santa Elisabetta.