This article aims to explore how an individual actor, embodying the role of the institutionalentrepreneur, legitimizes new corporate reporting practices. This study is based on a longitudinaland explanatory case study of an Italian listed public utility, operating in the electricity sector,which has recently implemented Integrated Reporting. Findings were analysed through thelens of institutional entrepreneurship, revealing that Integrated Reporting can be implementedthrough the legitimizing activities carried out by the corporate social responsibility manager.This organizational professional, with strong competences and intrinsic engagement, efficientlyuses available resources and gains support from various organizational groups through intensenetworking. A substantial change in corporate reporting practices can influence the positionof the institutional entrepreneur who originally triggered the change process. The institutionalentrepreneur first moves from the periphery to the centre of the organization and then sharessuch central role with other organizational professionals once the change has been implemented.