Reducing firms’ environmental impact is a question now widely addressed in the management and sustainable development literature. Increasingly, new frameworks and tools are introduced to help business better measure and reduce their impacts on biodiversity and ecological systems. Yet, the specific issues faced by environmental sector companies that try to develop commercial services dedicated to the management of ecosystems are today still largely unexplored. For them, the core issue regarding sustainable business model i nnovation is not so much the one of ‘greening’ their supply chains, but rather of imagining, designing and proposing original services and business models for the creation of ecological value. In this paper, we distance ourselves from existing propositions to use economic valuation and standard monetary pricing of biodiversity and ecosystem services (the benefits humans receive from good ecosystem functioning) as a basis and precondition for the development of new biodiversity markets and business models. Instead, we suggest that “ecological value”, defined in most general terms as the improvement of ecological systems’ quality (i.e. higher biodiversity richness, better freshwater quality, improv ed ecosystem functioning, etc.), is always co - defined and co - created by multiple stakeholders in a given ecological, organizational and political context. Therefore, we call “conservation - oriented business models” negotiation models for firms who engage in the co - definition and co - creation of ecological value in various contexts, by proposing legitimate and valuable commercial contributions to the collective management of ecosystems. This paper is based on a three years long action - research conducted at th e heart of a leading French water company. The firm’s core business model is based on long - term contracts with municipalities for the provision of water services. The profitability of this core business model is continuously eroding since the beginning of the 2000s, due to higher competition on prices 45 and the rise of ecological threats on the quality and availability of water resources that require new investments. To diversify its portfolio of ac tivities, the company has adopted in 2009 an explicit strategy of developing new commercial services and innovations to improve the collective management of freshwater quality (freshwater quality monitoring, voluntary plans to reduce agricultural pollution s etc.), and more largely, to contribute to the restoration of the landscape’s ecological quality (ecological restoration, biodiversity offsetting, artificial wetlands, adaptation to climate change, etc.). The paper first describes how managers experiment different practical paths to develop new business models supporting the development of such services in various commercial and ecological settings in France. We show the diversity of challenges and obstacles that they encounter such as: issues of legitima cy and license to operate as they try to establish relationships with new stakeholders and clients in the domain of environmental management; issues of quantification of the ecological value generated by their new services, etc. The paper then describes how we used theoretical frameworks adapted to the collective management of ecological issues, as well as action - research methods such as focus groups, scenario building and simulation games to design four original conservation - orie nted business models dedicated to ecological value co - creation. We show how each model responds to very different possible contexts where public funding and public initiative for ecological restoration is rather high or low. We describe how, in each of the four models, the company can develop different “services for ecosystems” value propositions that combine ecological engineering services, ecosystem assessments and accounting services, and organizational activities. The paper then discusses how in each o f the four models, the company needs: (1) to negotiate its value proposition with different types of clients; (2) to organize various relationships with different communities of stakeholders/partners in order to co - create long - term ecological values; (3) t o play different roles, on the basis of different moral values, in order to be accepted as a legitimate player in ecological systems management and justify the remuneration and profitability of its contributions; (4) to develop ecological accounting models and tools in order to quantify, monitor and support the negotiation and management of the ecological value co - creation processes