The European Union (EU) 2020 Biodiversity strategy will soon come to an end and may not have been as successful as envisioned. In the current context of the global biodiversity crisis, the European Commission, the research community, and broader society cannot risk another, likely ineffective, attempt by the EU to halt biodiversity loss after 2020. Through the development of the EU post 2020 Biodiversity Strategy, the scientific community of the ALTER-Net and EKLIPSE networks saw a unique opportunity to make a difference for biodiversity in Europe by better involving scientists, policy makers, and society. We developed an innovative, transparent, and collaborative process—called the multiphased, iterative, and consultative elicitation of scientific expertise (MICESE) method. This process allowed us to produce a set of 12 key messages developed by scientists for the EU to prioritize in the development of the new post 2020 biodiversity strategy. These key messages were structured according to their systemic value, scale, and nature. We provide insights and analyses of the new MICESE method before reflecting on how to improve the future involvement of scientists in science–policy interfaces.