In recent years, new technologies have led to disruption and change within most industries, resulting in the emergence of digitally-born start-ups. The purpose of this thesis is to complement the scarce theory about what the drivers of business model adaptation in start-ups consist of and how the adaptation process is managed to stay competitive. The findings not only provide theoretical contributions, but can also help managers to steer their start-upsthrough the growth phase.The research is set within the realms of business model theory in the strategic management field. An exploratory study with a qualitative, inductive approach was chosen to gain insights into the business model dynamics of nine firms from the fintech and healthtech industries.The results showed that foreign market adaptation, industry dynamics, funding, and legislation are perceived challenges, whereas legislation and exogenous shocks are opportunities that drive business model adaptation in start-ups. The business model elements of strategic decision-making, resources and capabilities, and network and partners were found to be integral to the adaptation process, as their core components not only need to be adapted to the environment but also aligned with each other. Those components should be revised in an iterative trial-and-error process driven by feedback.