The purpose of the study is to substantiate the effectiveness of innovative and investment activities of enterprises within the functioning of eco-industrial parks in the circular economy context. The methodological basis of the research is system and synergistic approaches, the application of which makes it possible to study innovation and investment activities of enterprises that are part of the eco-industrial park as certain subsystems, which in the end, as components of the park, provide a synergistic effect. It is substantiated that the unification of production enterprises within eco-industrial parks consists in a more integrated interaction of enterprises, including through joint investment. The proposed methodical approach to calculating the efficiency of innovation and investment activity of enterprises included in ecoindustrial parks and its approval proves the possibility of obtaining a positive effect from investment activities and investment in innovative projects by enterprises united in ecoindustrial parks in the context of the circular economy. The analysis of the share of production enterprises that implement innovations, as well as the share of the volume of innovative products sold to the total volume of manufacturing enterprises prove the need to intensify the innovative activity and the introduction and development of eco-industrial parks. The advantages of innovation and investment activities within eco-industrial parks in the circular economy context are highlighted.