Abstract: An accessory carrier case assembly mountable on a support structure, such as the underside of a vehicle trunk lid, includes an elongated case having a latchable bottom tray and top lid. The bottom tray and top lid are padded with a foam material. The bottom tray has an interior structure defining different compartments for various items of fishing equipment. The top lid and bottom tray have sufficient interior space for accommodating fishing rods therein. The accessory carrier case assembly also includes an arrangement of rigid mounting brackets, flexible holding straps, and flexible hook and loop releasable fastening strips for supporting the carrier case on the underside of the trunk lid. The releasable fastening strips are applied respectively on the holding straps and on either the top lid or bottom tray of the carrier case for releasably supporting the carrier case from the underside of the trunk lid.