This study aims to explore the interactive effects of safety investments, safety culture and project hazard on construction safety performance. Data were collected using multiple techniques from 47 completed building projects in Singapore. Data were analyzed using correlation analysis, regression analysis, moderation analysis and mediation analysis. The results show that: (1) safety performance improves when there is a higher level of safety investments, a higher level of safety culture or a lower level of project hazard; (2) the effect of any individual factor on safety performance varies with the changes in other factors; (3) the effect of voluntary safety investments on safety performance is mediated by safety culture; and (4) the relationship between accident frequency rate and accident severity rate is moderated by project hazard level. The study suggests that safety performance of building projects is determined by the synergy effect of safety investments, safety culture and project hazard.