The parish church of Santa Trinità, built in 1654, is the main church of Sassello and the finest of its buildings. The interior is decorated with frescoes by Bruschetto — a 17th-century local artist — which cover the vaulted ceiling and apse in elaborate Baroque compositions.
The church also contains several notable altarpieces and carved woodwork. The oratory of the Disciplinati nearby, a short walk from the main church, holds a wooden sculpture group by Anton Maria Maragliano, the leading Genoese sculptor of his generation, whose processional sculptures appeared throughout Liguria in the late 17th and early 18th centuries.