This study aims to explore the feasibility of transforming CO2 into lipids for biodiesel by integrating anaerobic fermentation and black soldier fly larvae (BSFL) bioconversion. The optimal conditions for CO2 and biowaste fermentation into volatile fatty acids (VFAs) were examined under different pH conditions. Moreover, we also explored the effects of different concentrations of VFAs solutions on BSFL lipid accumulation. The results showed that the optimal pH was 7 for the production of VFAs, and the maximum acetate and butyrate concentrations were 10.11 and 3.56 g/L, respectively. Feeding BSFL with this fermentation broth increased their lipid content by 2630% compared with the control. Moreover, the optimum concentration of VFAs solution was 26 g/L to enhance the lipid content of BSFL. This work provides an innovative route of great potential to reduce the cost and energy consumption to fix CO2 in an anthropogenic carbon cycle: the VFAs from CO2 and organic waste do not need to be extracted from fermentation broth, and can be directly used for lipid accumulation in BSFL for biodiesel. (C) 2019 Elsevier Ltd. All rights reserved.