This study investigates the structural optimization of lightweight three-layer panels made from industrial hemp shives (core) and hemp fibers (faces) as a sustainable alternative to wood-based materials in furniture manufacturing. Panels with target densities of 400–600 kg·m−3 and face-layer contents of 30%–50%were produced and tested to European standards. The optimal configuration—600 kg·m−3 with ~37%–41% face layers—achieved a modulus of elasticity up to 3750 N·mm−2 and a bending strength (MOR) up to 21.57 N·mm−2. Across the design space, water absorption ranged from ~83% to 162%, and the minimum thickness swelling was ~29%, indicating that while the mechanical properties meet the requirements for P2 particleboards (EN 312) and in some cases approach MDF benchmarks for dry use, thickness swelling remains above the EN 622-5 limit (12%) and thus precludes MDF classification. These findings demonstrate the technical feasibility of hemp shive–fiber panels and underscore the need to balance density and face-layer ratio to avoid loss of core densification at excessive face contents. From a sustainability perspective, the use of rapidly renewable hemp and agricultural residues highlights the potential of these composites to support resource-efficient, low-carbon furniture production, while future work should target improved water resistance through binder and process modifications.