Financial technology has grown at an unprecedented pace, with Islamic fintech emerging as a distinctive innovation that complies with Shariah principles. This research examines the intermediary role of digital self-efficacy in Islamic fintech adoption in Indonesia, a country with the world’s most significant potential for Islamic finance. Data were collected from 353 respondents through a survey conducted by the Indonesian Sharia Fintech Association (AFSI) and analyzed using the SEM-PLS approach, which is suitable for predictive and mediation analysis in complex models. The findings show that Islamic financial literacy and trust are the strongest predictors of digital self-efficacy, while customer experience, facilitating conditions, and social influence exert smaller yet significant effects. Digital self-efficacy strongly predicts adoption and partially mediates the influence of all antecedents on Islamic fintech adoption, explaining more than 60% of the variance in both constructs. Theoretically, the study extends existing adaptation frameworks like TAM and UTAUT through integrating insights from social cognitive theory, highlighting the importance of psychological factors in technology adoption. Practically, it underscores the need to strengthen financial literacy, build trust, and enhance digital self-efficacy to reduce barriers, expand financial inclusion, and accelerate the rise of Islamic fintech in alignment with the Sustainable Development Goals.