We explore digital entrepreneurship in the banking and financial sector through the concept of organizational ambidexterity (AO), which is defined as the balance between the exploration of new activities and the efficient exploitation of existing activities. We examine how AO can help meet the challenges of viability and sustainability faced by fintech, which are startups that combine the attributes of digital technologies and finance. Based on interviews with founders/managers, our results show the development of a “mixed ambidexterity”, which combines exploration and exploitation activities. Contrary to the dominant scientific discourse, different forms of ambidexterity do not in themselves constitute “pure” or opposed forms. They can be combined using managerial levers to develop “multi-ambidextrous” structures, particularly in dynamic and competitive technological environments. Our research contributes to the entrepreneurship literature by a reflection through the managerial concept of AO. We propose an entrepreneurial approach based on entrepreneurs’ capacities to reconcile exploration and exploitation. We therefore extend our understanding of entrepreneur behavior through the concept of AO and address the lack of research on this concept in the entrepreneurship literature. Theoretical and practical implications are proposed for designing ambidextrous entrepreneurial organizations.