In the current study, a new CSR disclosure (CSRD) scale was formulated which is rigorously based on the CSR guidelines of the Companies Act, 2013. From 10 industries, total 100 companies were sampled out of which 27 were public and 73 were private. The extent of CSR disclosure (both mandatory and voluntary) and transparency levels of the 100 companies, and the public-private sectors were evaluated for an extended period of study of 11 years (2009–2019) which includes both the pre- and post-Companies Act period. Results showed that the maximum extent of disclosure was found for the ‘environment’ category. The overall extent of disclosure by the 100 companies was not so high (35%). However, the public sector (40%) disclosed more than the private one and even exceeded the overall extent. The disclosure extent made a remarkable jump (more than 2 times) during the post-Companies Act period compared to the pre-Act era. Furthermore, post implementation of the Companies Act, the transparency level of the companies increased drastically than the pre-Act period, 4% to 43% adequate transparency, and some even showed high transparency level. Overall, the public sector displayed more transparency than the private one.