AbstractThis paper provides a deeper understanding to the development and implementation of a Sustainability Balanced Scorecard in the Port Authority of Cartagena, under exploratory research. Open‐access documents available on different websites were used as data sources combined with semi‐structured personal interviews, which took place at the highest level of the organisation from September 2021 to December 2022. The strategy developed by this government unit has changed over the years, until 2018 when a new review, led by the Planning and Management manager, established a turning point in its sustainable strategy with the introduction of the Balanced Scorecard, resulting in a major internal change for the organisation. The creation of the Strategy Planning Office, external advice from strategy‐expertise consultants, IT solutions acquisition adapted to the new scenario, and several internal organisational changes, have been vital in this successful process. The Balanced Scorecard has been shown to be helpful in disseminating the sustainable strategy at all levels of the company: environmental and social actions were confined for years to the Sustainability Department, functioning as isolated actions, but now, they have reached the strategic level involving the whole organisation as part of the company's strategy. This successful process has put this organisation at the forefront of other Spanish ports, providing other port authority managers with a useful framework that can help them in their attempt to implement sustainable strategies by using the Balanced Scorecard—a framework not only valid for ports but which can also be extended to other government units.