The 4th International Conference on New Business Models (1-3 July 2019, in Berlin) aimed to motivate vivid discussions on new business models with the potential of contributing to a sustainable development of the natural environment and humanity. Corresponding business models and business activities require entrepreneurs and innovations that foster transitions to future-fit societies, building on values such as responsibility and justice. This endeavour, in turn, requires much more progress in inter-, multi-, and transdisciplinary research. Against this background, the 4th International Conference on New Business Models gathered theoretical and empirical contributions that bring together insights from the fields of sustainable entrepreneurship, innovation, and transition studies on the one hand, and business models for sustainability on the other hand. The contributions have been collected in the full conference proceedings.