This paper proposes a hierarchical decision model for efficient and fair coexistence of Wireless Fidelity (WiFi) and heterogeneous cellular networks with device‐to‐device (D2D) communications. The first submodel is an allocation game formulated to model the data rate gain possible through the deployment of D2D communication in cellular networks. This is to guarantee that the Long‐Term Evolution (LTE) network is optimally utilized before offloading traffic to WiFi small cells. The second submodel is a Markovian model proposed as an optimal spectrum sharing scheme that guarantees efficient spectrum utilization and interference reduction in LTE‐WiFi heterogeneous networks (HetNets). Simulation results verify that the proposed decision model not only provides a more spectrum efficient sharing scheme but also shows better network throughput while ensuring fairness in spectrum access for WiFi users.