From simple organizations as gateways for goods and passengers, ports have evolved and transformed into complex organizational systems with multiple functions. Besides providing cargo, logistics, and other kinds of services to its customers, modern ports engage in the development of their hinterlands. Sustainability, evolving from environmental actions over the years, has become the core of many modern ports’ approach towards hinterland development and port competitiveness. While the literature is concerned with and presents examples of large ports implementing sustainability initiatives, the literature is scarce on smaller ports. This article addresses this gap by exploring qualitatively the case of the Port of Aalborg, a medium-sized port in Denmark, and its evolution towards using sustainability for port and hinterland development. The research focuses on the actions behind environmental development at the port. Its evolution is mapped and explored using the analytical framework developed based on the (larger) ports’ development and their roles. The findings from the Port of Aalborg case exemplify how smaller ports can evolve to drive the sustainable development of their hinterlands and contribute to a better understanding of this kind of port.