The study proposes a framework to establish the isomorphic nature of corporate social responsibility (CSR) expenditure for Indian companies. Isomorphism in NIFTY-50 companies of India was analysed using the Herfindahl-Hirschman Index (HHI) and Shannon-Weiner Index (SWI). This was followed by a qualitative study of six organisations as a case study and an analysis of interviews with 29 managers of different organisations involved in CSR practices. NIFTY-50 companies were found to be isomorphic. A study of six group companies and the analysis of interviews of 29 CSR business managers, found that isomorphism in Indian companies can be termed as long-term social legitimacy-seeking behaviour. A company’s relationship with society shifts from seeking internal and external legitimacy to having a symbiotic relationship with society. In the long-term, the company uses its CSR to seek legitimacy at all levels (from the grass-root level community to the highest level of state actors). The study was done for the pre-COVID-19 financial years starting 2014–2015.