Real-world labs are witnessing continued growth and institutionalization in the field of transformation-oriented sustainability research, as well as in adjacent disciplines. With their experimental research agendas, these labs aim at sustainability transformations, however, there is still a need to improve the understanding of their impacts. Drawing from this Special Issue's contributions, we offer a broad overview of the impacts achieved by various real-world labs, highlight the diverse areas and forms of impact, and elucidate strategies as well as mechanisms for achieving impact. We present methodological advances, and address common challenges along with potential solutions for understanding and realizing impact.