The Diocesan Museum, opened in 1927 by Archbishop Alessandro Lualdi, is located inside the Archiepiscopal Palace of Palermo, built in the mid-15th century by Archbishop Simone Beccadelli of Bologna. Some Gothic elements of the 15th-century layout are still visible today, such as the portal bearing the coat of arms of its founder. The palace underwent several changes starting in the 16th century, visible in both the façade and the interior, which in the 18th century became one of the most magnificent in Palermo.
The Diocesan Museum, originally housed on the second floor of the building, was moved in the 1980s, at the behest of the then Cardinal Salvatore Pappalardo, to the reception halls, currently under restoration, overlooking Via Matteo Bonello.
Initially, the collection only included the sculptures present inside the Cathedral, before it underwent the transformations of the Renaissance era. Later, it also included works from destroyed or decommissioned churches and, in the 1970s and 1980s, works stored in churches that were unsafe for security reasons. It thus came to encompass eight centuries of Palermo church history from the 12th to the 19th century.