<p>Order allocation is one of crucial and important decisions which determines the efficiency and effectiveness of a supply chain. Several factors such as product quality and order delivery have been recognized to have significant impact on company’s order allocation on their suppliers. Sustainability issue makes the order allocation becomes more complex as well as the uncertainty and insufficient information about materials availability and market demand. Among the economic, environmental, and social aspects of sustainability, the first two aspects are commonly considered in the optimization model development. Carbon emission has become the global supply chain concern and common environmental metric in the model development. In this research, a multi-objective fuzzy mixed integer linear programming model is developed to determine the optimal order allocation considering defect, late delivery, and carbon emission under cap-and-trade carbon policy. The results of the analysis indicate that decision-makers (DM) should set the parameters’ values of α and γ to achieve satisfactory results. When the DM sets a higher value of α, better solutions are obtained. The DM should also consider product pricing, as higher prices may result in more defects and late deliveries.</p>