Cogeneration or combined heat and power (CHP) is a proven energy-efficient technology for its ability to generate electricity and heat energies concurrently. In an industrial park, implementing the cogeneration energy system by different facilities requires a symbiosis synergy to determine the optimal design. Previous works have studied the cooperative coalition among tenants in an eco-industrial park. In this paper, the cooperative game theory explores the potential coalition between different facilities for optimal cogeneration implementation. The integrated optimisation framework is proposed to (1) minimise the overall cost and environmental emission constraints and (2) rationally allocate the investment costs and profits among the collaborating parties. The optimisation problem is solved as a mixed-integer linear programming (MILP) model by using GAMS software. The obtained optimal coalition has a TAC of RM 7.85 x 106/y and assigns the iron-fabricating facility with a heat-to-power ratio of 2 as the anchor entity. The developed framework is crucial to laying the groundwork for macro-level cogeneration and peer-to-peer electricity trading planning in Malaysia.