Mass reduction of automotive components enhances vehicles' performance and extends their driving range. However, lightweight construction typically leads to noise and vibration issues. Hence, the development of lightweight components must go in tandem with advancements in the field of noise and vibration. This work focuses on the lightweighting of the gearbox housings (GBHs) and on the introduction of vibroacoustic metamaterials to improve their Noise, Vibration, and Harshness (NVH) characteristics. Topology optimization methods were used to reduce the mass of a GBH. Its noise emission was evaluated numerically, before and after the mass reduction. Locally resonant metamaterial (LRM) solutions were applied in the GBH and then tested in numerical simulations. This analysis showed the LRM solutions reduce the emission of noise in the predicted band gaps (BGs), while also providing significant attenuation across the entire frequency spectrum under consideration. The experimental results confirmed the effectiveness of the LRM attenuation concept and the trends observed in the numerical results. Vibration was also attenuated in parts of the GBH where the LRM was not applied. Attenuation of in-plane housing vibration was also observed. The proposed LRM solutions are lightweight, passive and low-cost solutions that can implemented in housings to enhance their NVH characteristics.