The Holy Trinity Roman Catholic Church in Kuldīga (built between 1640 and 1642) is the town's only Catholic church, located in its historic center. It was commissioned by Duke Jacob Kettler at the request of the King of Poland to seal his succession to the Duchy of Courland.

The exterior features a simple, restrained Italian Renaissance design, which stands in stark contrast to its interior—renowned as the most luxurious among all Catholic churches in the Kurzeme region. The inside is lavishly decorated in 17th-century Baroque and rich Rococo styles.

Today, the church is a protected national architectural monument and an active sanctuary, standing next to the Convent of Our Lady of Sorrows.