The world supply chain highly depends on air, sea and land transportation, which is a main source of greenhouse gas (GHG) emissions such as CO₂. While lean business strategies are focused on improving inventory turnover through the supply chain, this can increase transportation and thus, increase GHG emissions. Particularly to reduce these emissions, and improve energy generation/consumption and sustainability, governments have incorporated energy taxes associated to CO₂ on transportation. However, these taxes only increase operational costs and do not imply a reduction in emissions. In this work an integrated inventory – transportation model is developed to support the reduction of CO₂ emissions and operational costs considering inventory management and route planning under uncertain demand. Based on real inventory and geographical data, the results of the model support evidence that inventory management can lead to reduce operational costs by 10.22% and CO₂ emissions by 36.58%. Additional reductions, up to 12.77% and 43.02% respectively, can be obtained if route planning is integrated. This can support companies to visualize how their operations contribute to CO₂ emissions and develop internal strategies to reduce them in accordance to their operational costs.