The Sierra de Cayey (English: "Cayey Mountains") is one of three subranges of the Cordillera Central mountain range in the main island of Puerto Rico.

It is demarcated from the eponymous main subrange of Cordillera Central by the San Cristóbal Canyon on the town boundary between the municipalities of Barranquitas and Aibonito.

From west to east, it is concentrated in the municipalities of Aibonito, Cayey, Guayama, and Patillas in the southeastern region of the island.

[1] Along with the Sierra de Luquillo in northeastern Puerto Rico, the Cayey mountain range is the smaller subrange of the Cordillera Central.

The Rio Grande de Loíza, which is one of the largest rivers in Puerto Rico, has its sources in this range within the municipality of San Lorenzo.