Why do rational, profit-orientated firms generously engage in corporate social responsibility (CSR)? Our study explores the real motives of speculative firms for CSR engagement and the hidden causality behind it. Using national survey data of privately owned firms in China, we find that corporate speculation positively influences firms’ engagement in CSR, revealing that CSR is instrumental and that firms use it as a tool to mask their speculative activities by building their reputations and buying ‘leniency insurance’ against potential penalties. Further, the relationship between speculation and CSR is less pronounced in firms with political involvement, revealing that the effect of political involvement as an informal institution somewhat protects speculators from potential sanctions without a CSR premium. We also discovered that the relationship between corporate speculation and CSR—as well as the moderating role of political involvement—is less pronounced among developed regions, revealing that the development of formal institutions can restrict the instrumentality of CSR and the effect of political involvement. Such findings have important implications for CSR in emerging economies.