Ecological infrastructure (EI) refers to ecosystems that deliver services to society, functioning as a nature-based equivalent of, or complement to, built infrastructure. EI is critical for socio-economic development, supporting a suite of development imperatives at local, national and international scales. This paper presents the myriad of ways that EI supports sustainable development, using South Africa and the South African National Development Plan as a case study, linking to the Sustainable Development Goals on a global level. We show the need for EI across numerous development and sustainability issues, including food security, water provision, and poverty alleviation. A strategic and multi-sectoral approach to EI investment is essential for allocating scarce public and private resources for achieving economic and social-ecological priorities. Opportunities to unlock investment in EI, both internationally and on the national level, are identified. This includes leveraging private sector investment into landscape management and integrating the costs of managing EI into public sectors that benefit directly from ecosystem services, such as the water sector and infrastructure development. Additionally, investing in EI also aligns well with international development and climate change funds. Investment in EI from a range of innovative sources supports global and national development, while complementing other development investments.