<p>Over the past few years, the expansion of e-commerce has led to a substantial rise in last-mile delivery operations. Within this scenario, retailers have primarily concentrated on enhancing service performance, frequently neglecting the sustainability consequences associated with economic, environmental, and social aspects. Consequently, the necessity of incorporating sustainability criteria into last-mile route optimization has become increasingly clear. To this end, recent research has developed linear programming models that address the Vehicle Routing Problem (VRP), including its associated formulations. Despite these advances, current approaches mainly focus on economic performance and only partially incorporate environmental concerns, leaving the social dimension insufficiently addressed. To tackle this limitation, the present research introduces a linear programming model designed to plan last-mile delivery routes while jointly reducing economic, environmental, and social impacts. Unlike existing models, the proposed model incorporates social considerations related to drivers’ workload and accident costs. To this end, a literature review is first conducted to identify the key indicators for each pillar of sustainability. Subsequently, the model is formulated and validated through its application in a case study, achieving an overall improvement of 43% in the impact on the three pillars compared to the initial situation. This overall improvement is made up of partial improvements in each pillar: the economic pillar accounts for 41%, while the environmental and social pillars represent 29% and 61%, respectively. Thus, the results demonstrate the applicability of the model for optimizing last-mile routes, while maintaining equilibrium among the economic, environmental, and social sustainability dimensions.</p>