Given the huge challenges agriculture has to face, both in Northern and Southern countries, a radical change in farming practices towards agroecology is required. Most scientific literature on the design of new farming systems describes de novo approaches, which focus on disruption and novelty, without any concern for the way to move from the current system to the innovative one. In this study, we highlight, for the first time, the particular traits of what we will call the step-by-step design approach. In this aim, we disentangled 9 case studies of practice change in commercial or experimental farms through the lens of theoretical frameworks derived from three scientific fields: design sciences, farming system research, and change pathways analysis. From data collected in each case study, and collective interactions among the authors of this paper, we identified commonalities across cases, in the aim to produce guidelines for actors willing to engage, characterize or support such design processes in the future. We thus show that step-by-step design appears as (i) a situated design process fueled by action, (ii) structured by iterative loops diagnosis – exploration – implementation – assessment, fostered by learning, (iii) progressively shaping a desirable unknown, (iv) supported by specific tools, and (v) intertwining individual and collective dimensions. This approach is well adapted to manage the agroecological transition: by its temporality, by its capacity to overcome knowledge gaps through learning, by its contribution to farmers' empowerment, and by its capacity to tailor solutions to local specificities. By doing so, it allows the progressive implementation of profound systemic changes. Finally, this article provides benchmarks to encourage increased Research & Development investment in this type of approach, contributing to open innovation, to enhance the agroecological transition.