The post-COVID-19 panorama presents serious economic and social challenges, prompting the European Union (EU) to allocate extensive funds to its Member States. The central financing instrument created for this purpose, NextGenerationEU (NGEU), requires the Member States to implement ambitious reforms to bring about green and digital transitions within their National Recovery and Resilience Plans (NRRPs). Despite innovative elements in NGEU’s decision-making process, legal basis and fiscal integration policy, the role of sub-state authorities in the context of multilevel governance (MLG) demonstrates a centralised tendency. In order to understand this issue, the management of NRRPs in the Spanish system of autonomous communities and Italian regionalism will be taken as emblematic case studies. Specifically, the constitutional significance of the MLG model in the context of the NGEU recovery package will be evaluated in light of the principles of solidarity, subsidiarity, proportionality and partnership. This paper ultimately aims to offer broader insights into NGEU’s role in the ongoing EU federalisation process and its shortcomings with respect to national decentralised systems.