Abstract. The article is devoted to the transformation of financial sector in terms of digitalization and creating sustainable financial ecosystems. The global financial ecosystem includes global, regional and national associations of financial institutions, regulators and other stakeholders, as well as financial ecosystems of individual countries. Creating a sustainable financial ecosystem on the national level is an important task and requires participation of the central bank as a regulator. Digitalisation of the economy as a whole and the financial system in particular contributed to the emergence of fintech companies and their rapid development. Nowadays remote technologies are widespread all over the world and there is growing demand for fintech services. In terms of digitalisation central banks need to be up-to date to improve national financial ecosystems. They are responsible for creating an adequate regulatory framework for regulation of fintech activities and at the same time stimulation of their development. Modern tendencies of the financial sphere regulation are analysed in the article. There is a trend among regulators worldwide to prioritize the development of fintech and to implement a ‘supportive’ regulation as well as introducing central bank digital currencies. The author outlines the main tendencies of the investments in fintech in the world. The main principles of sustainable financial ecosystems functioning in terms of digitalization are highlighted. On the basis of conducted analysis the author provides recommendations for the development of the sustainable financial ecosystem in Ukraine in modern economic conditions.