This study explored corporate social responsibility practices in selected public libraries in south-west and north-central Nigeria. The study adopts multiple case-study design, and qualitative research approach. Interview was used to collect data from a total of fifteen (15) participants. The study found that the public libraries do not have written CSR policy. Results showed that the public libraries engaged in social support, social change, socio-cultural activities, and COVID-19 social support. Findings showed that public libraries provide charity through book donations/gifts and provision of information to library users. It was revealed that public libraries advocate for, and participate in, periodic environmental sanitation. Results showed that the libraries remove what the librarians consider as morally decrepit information materials from the shelves, which means they aid censorship. The study showed that public libraries adhered to the ethics and guidelines of Librarians' Registration Council of Nigeria (LRCN) to a minimum extent since the Council has partially failed in their supervisory role. The study concludes that public libraries have their in-house ethics and policies that guide the library staff, users, attendants, and visitors. The study recognized that public libraries provide economic viable information to users, which enable them get improve their career, secure employment, and learn vocation. This study contribute that public libraries are essential in ensuring and meeting sustainable development goals via responsible CSR practices.