Corporate philanthropy strategy integrated into the core business constitutes a novel vision and a little‐explored field of study with regard to corporate social commitment. The goal of this study is to analyse how the diverse ways of managing and assuring philanthropy can be considered signals of a firm's social commitment and consequently affect its market value. In addition, the analysis considers whether the business sector moderates those relationships. We aim to provide a comprehensive vision of corporate philanthropy and its effect on market value. From a sample of 965 firm‐years, of 193 firms from 2011 to 2015, we found that the market responds positively to the professional, independent management of philanthropy via a foundation, in preference to donations, and welcomes external assurance of corporate philanthropy as a set of actions that improve the perceived reliability of philanthropic activities. In addition, we observe a moderating effect of the business sector on the relationships among corporate philanthropy, assurance and the company's market value. The main contribution of this study is the provision of new evidence of how corporate philanthropy and its assurance are effective signals that reduce the information asymmetries between firms and investors, affecting company market value positively.