Rapid transformation to meet the Paris 1.5oC climate target requires greater attention to be given to the role of innovative low carbon early stage businesses and the public sector’s role in addressing finance gaps for longer horizon investment requirements. As entrepreneurs require different forms of finance as their businesses grow and move up the ‘finance escalator’, we explore the role of public sector support for grant, equity, debt and new forms of crowd funding finance. These funds can enable individual sustainability focussed businesses to access finance and encourage finance into new areas through having a demonstration effect. We conclude that a finance ecosystem approach is required that ensures complementary forms of finance for low carbon investment are connected at local, national and international scales, alongside support to build entrepreneurial skills and investment readiness. There is also a need for better evidence of the role of public sector support and where there is greatest impact on climate change.