The present study highlights the importance of green investment in achieving the goal of sustainability. Several studies have been conducted to explore the factors affecting sustainable development. However, the literature on the importance of green investment in affecting sustainable development from the perspective of enterprise cost and government guidance is scant, and the moderating effect of financial efficiency is also ignored. Thus, this study is based on the social and economic data of 31 provinces in China from 2009 to 2021, the study evaluates the level of sustainable development of each province and combines green investment, financial efficiency, and sustainable development into the research framework from the dual perspectives of government and enterprises to explore the relationship among the three, which can make sustainable development efficient and balanced. The results show the following: (1) Government green investment has a “U-shaped” spillover effect on sustainable development; (2) Corporate green investment has an inverted U-shaped nonlinear effect on sustainable development; and (3) Under the adjustment of financial efficiency, government green investment has a “two-stage” promoting effect on sustainable development, and corporate green investment has an inverted U-shaped nonlinear effect on sustainable development. Based on these findings, it is recommended that increase the amount of government green investment, ensure the sustainable amount of corporate green investment, and promote coordinated financial and economic development.