The article studies the essence and peculiarities of using social and solidarity financing mechanisms in the modern economy. The development of the social and solidarity economy, which balances the goals and priorities of sustainable development with the goals and values of the market economic system, raises the issue of financing organizations in this sector that do not always adhere to economically sustainable business models. Companies of the social and solidarity economy are a tool for forming a new and efficient system of the national economy, providing environmental protection, cultural development, education, healthcare, social security, implementation of civil society initiatives, etc. However, as they pursue primarily social rather than economic goals, the issues of their financial support and achieving financial sustainability in the long-term context are being raised. The article analyzes the transformation of social and solidarity financing mechanisms, defines their essence in the current context, and identifies the primary sources of social and solidarity financing by potential providers. The latter include individuals, participants, shareholders, other stakeholders, foundations and philanthropic organizations, financial intermediaries, and public authorities. The next stage of the study systematizes the main types of social and solidarity financing mechanisms in the modern economy, including traditional (donations, grants, loans, subsidies, etc.) and innovative forms (ethical, impact investing, tolerance capital, social stock exchanges, etc.). Based on the analysis, the authors substantiate the reasons for the growing role of social and solidarity financing in the modern business sector, which include an increase in demand for qualified personal and social services as a result of the long-term COVID-19 pandemic and Russian aggression in Ukraine; and the actualization of social inclusion issues due to the growing social inequality and uncertainty of specific population groups and the need for their social adaptation.