<p>Mobile data offloading has recently emerged as a promising technique to manage the increasing data traffic demand from mobile users. This method is applied in overlapping heterogeneous networks—such as Wi-Fi and cellular systems—where the capacity of one network can assist or complement the other. In such environments, improving the performance of one component network directly impacts the overall offloading efficiency. In this paper, we propose a novel cooperation-based framework at the MAC layer of Wi-Fi networks to enhance the offloading process using an intelligent relay node selection. The relay selection is performed by a newly defined metric called the Cooperation Delay Ratio, which enables low-latency two-hop communication between user nodes and access points (APs). The proposed cooperative approach is compared with a non-cooperative baseline in terms of four key performance indicators: throughput efficiency, offloading ratio, energy efficiency and AP deployment. Simulation results demonstrate that the cooperative scheme achieves up to 42.5% and 48% improvement in throughput efficiency and energy efficiency respectively, increases the offloading ratio up to 1.43, and reduces AP deployment requirements by up to 29% compared to the non-cooperative mode. These enhancements highlight the potential of the proposed framework in optimizing resource allocation, improving network performance and reducing operational costs in next-generation heterogeneous wireless systems.</p>