This research explores the ecosystemic legitimacy of public entrepreneurial support structures. Entrepreneurial ecosystems are fully integrated into territorial development policies, whether to stimulate job creation or innovation. However, with a national debt in excess of 110 points of GDP and a deficit in excess of 4% since 2020, France's public finance crisis is calling into question the effectiveness of state and local government spending at all levels. We are therefore seeking to understand how support structures, mostly financed by public funds, are attempting to strengthen their ecosystemic legitimacy. Through an exploratory qualitative methodology carried out in the Hauts-de-France entrepreneurial ecosystem, we reveal the practices and legitimization mechanisms used by these structures. These results may be useful for any support actor wishing to strengthen the perception of legitimacy of its funders and ensure its survival.