A bra liner is an apparatus that conforms under a breast and is positioned in between the breast and a bra cup. The apparatus includes a flat liner body and at least one piece of adhesive. The flat liner body presses against the underside of a breast and an inner surface of a bra cup. The flat liner body includes an absorbent layer and a backing layer. The absorbent layer collects and retains sweat from the breast. The absorbent layer is connected across the backing layer. The absorbent layer and the backing layer are coextensive with each other. The at least one piece of adhesive is distributed across the backing layer. The at least one piece of adhesive is fixed onto the backing layer, opposite to the absorbent layer. The apparatus further includes a sealing sheet to prevent the at least one piece of adhesive from sticking to unwanted surfaces.