A castle chapel is a house of worship that belongs to and is on the grounds of a castle or a palace, and which is not a parish church. It may be free-standing or part of the main structure.

The chapel belongs to the castle or palace, rather than merely standing nearby. It can be an enclosed worship space within the residence or a separate building on the grounds; neither arrangement requires a particular size or architectural style.

A parish church has parish rights, which distinguish it from this chapel even when it is inside castle grounds. A monastery chapel and a university chapel have different institutional affiliations.