The patron of Trevignano Romano is Saint Bernardino of Siena, celebrated on 20 May.
On Ferragosto, 15 August, a nighttime procession is held on the lake, the culmination of the festivities honouring the Assumption of Mary into heaven. Every first and third Sunday of the month, a crafts and antiques market is also held in Piazza del Molo and along the lakefront. The town holds the Church of Santa Maria Assunta and the Porta dell'Orologio.
