Many countries are reshaping their agricultural policies to better enhance biodiversity and ecosystem services (BES) in farmlands, but measuring the effectiveness of policy instruments in BES delivery is challenging. Using the European Agricultural Policy as an example, we propose the application of a farming systems (FS) approach as a cost‐effective tool for linking policy design and expected BES outcomes. On the basis of available data from subsidy payment agencies, such an approach can identify groups of farms that share similar management practices as well as the associations between FS and corresponding BES potential, and improve modeled outputs of farm management responses to policies and other drivers of change. We describe how this relatively unexplored source of information can help to support applied ecological research and relevant policy, and call for these data to be made available across Europe and elsewhere.