Implementing the sustainable development goals (SDGs) adopted at the UN Summit in September 2015 specifically invites the creation of “an integrated, holistic, multi-stakeholder approach”. This implies the need for systems thinking in practice, a tradition that draws on systems theories, tools and techniques able to facilitate better conversation and cooperation between agencies. As an approach it goes beyond development of competencies through formal education programmes. This paper focuses on SDG 17—the means of implementation—and the role of systems thinking in practice for supporting both competence and SDG implementation capability. Two inter-linked initiatives led by systems thinking practitioners in the field of sustainability science are reported; one is an action research inquiry exploring the praxis (theory-informed-action) challenges of applying systems thinking in practice in contemporary workplaces ranging from in-field development projects to government administrations and business ventures, and another which built on the findings from this inquiry—a proposal for developing an action-learning platform for SDG implementation. Experience suggests that implementing SDGs requires not only competence in systems thinking but a capability of putting systems thinking into practice in a dynamic way, as praxis. The proposed action-learning platform can also be regarded as a learning laboratory in the sense that it will offer learning support and a chance to collaborate and experiment. This platform aims to be co-designed with multi-agency practitioners from international development, government planning, business/social enterprise and NGOs. The proposed platform draws on open-source resources, and ideas of social learning, developmental evaluation and systems thinking in practice traditions.