Exergoeconomic assessment of a multigeneration system, which is fed with a mixture of natural gas and syngas produced from municipal solid waste gasification process, has been conducted under climatic restrictions of both hot and cold seasons. In the basic state of the 1st scenario, for the constant net power of 30 MW and 50% mixing ratio, exergy efficiency and total cost rate of the system are 27.92% and 1328 USD/h in summer, and 33.81% and 1246 USD/h, in winter, respectively. Moreover, the total relative cost difference in the summer is considerably higher than that in the winter. In the basic state of the 2nd scenario, for the constant fuel mass flow rate of 1.5 kg/s, the system's annual exergy efficiency, annual total cost rate, and payback period are 30.79%, 1166.4 USD/h, and 2 years, respectively. The optimization has been performed based on the genetic algorithm considering two objective functions. The optimization results revealed that, the system's annual exergy efficiency and annual total cost rate got improved from 30.79% to 32.37%, and from 1166.4 USD/h to 796.52 USD/h, respectively, while the payback period increases from 2 to 2.1 years. The complete results of parametric studies are also provided for both scenarios.