Disclosed are a wafer carrier assembly and a chemical mechanical polishing apparatus including the same. The present wafer carrier for a chemical mechanical polishing apparatus comprises: a wafer carrier head rotatably mounted on the apparatus, having a lower surface for contacting a wafer; a retaining ring attached to the lower surface of the wafer carrier head, for retaining or preventing the wafer from moving from the wafer carrier head during rotational motion thereof; and a guard ring attached to the lower surface of the wafer carrier head a distance outside the retaining ring.