The co-patron of Ariano nel Polesine is Saint Cajetan of Thiene, celebrated on 7 August with the Feast and Fair of Ariano capoluogo, in the Oratory of San Gaetano da Thiene.
The Fiera di Ariano, of medieval origin, was established in 1690 and set in September; as devotion to Saint Cajetan grew, it was probably moved earlier to August. The parish patron, Saint Mary of the Snows, is instead celebrated on 5 August. The town also holds the Church of San Basilio.