In its most recent report, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) announced an unprecedented dangerous decline in biodiversity, one of the planetary limits that are currently being surpassed. The results and trends of socio–ecosystemic problems oblige us to attempt to understand and address the global crisis. Socio–ecosystemic problems are not only ethical and moral challenges but also ones of interest and security, since the financial resources available will be insufficient for people immersed in a sick and dysfunctional society. In this sense, science plays a central role in offering alternatives. This work is a theoretical construction, based on complexity and transdiscipline, that aims to offer these alternatives. It is enriched by several areas of knowledge, with the objective of broadening the interpretation of sustainability and overcoming some of the limitations of existing approaches through the recognition of the objective and subjective relationships between humans and ecosystems. Socio–ecosystemic sustainability is an adaptative process, taking the principles of strong sustainability and autopoiesis as an explanation of living and the processes that maintain and reproduce it. It is argued that goals centered on a vision of economic growth are not coherent with the natural processes of the biosphere—as shown by thermodynamics and complex systems—nor, indeed, with a functional society. The health and life on planet is a compelling reason for seeking dialogue between individuals and coherence in the three dimensions of socio–ecosystem sustainability.