The transformation from traditional financial methods to the adoption of new financial technologies is a key challenge for micro and small business enterprises in ensuring sustainability. Therefore, the purpose of this study is to identify the key factors of financial literacy and examining their significance in adoption of FinTech by MSEs in Odisha that leads to sustainability of the firm. The study has been conducted using the MCDM technique integrating grey Delphi for relevant factor identification and Fuzzy AHP for prioritizing the factors of financial literacy. In total, 33 financial literacy factors were initially identified through extensive literature review, which were reduced to 18 factors using grey Delphi. Further, these factors were prioritized on the level of their significance towards FinTech adoption, using fuzzy AHP. The results of the study highlighted that financial knowledge holds greater significance among all four criteria of financial literacy, i.e., financial knowledge, financial behaviour, financial attitude, and financial training, towards adoption of FinTech ensuring sustainability in MSEs. The prioritization of the factors further revealed that knowledge of current products and services, evaluation of FinTech products, expenditure behaviour, assurance for the future security, and financial education have the most significant impact on the adoption of FinTech services by entrepreneurs. The study is innovative as it shows the importance of financial literacy factors in influencing the adoption of FinTech by micro and small businesses, which helps in ensuring firms’ sustainability. The results of the study have come up with some key factors, which need to be considered at priority basis if an MSE is willing to adopt FinTech services for its operations to ensure sustainable practices.