Fatalities, injuries, and illnesses continue to occur in the construction industry (CI), despite efforts made by clients, designers, and contractors. The lack of collaboration between these project actors and construction health and safety agents (CHSA) remains a challenge for both construction professionals and academics. Given the urgent need for CHSA to collaborate with other construction project members, this study proposes a model for improving CHSA collaboration and its influence on health and safety (H&S) performance. The exploratory sequential mixed method, which included a Delphi study and a questionnaire survey, was adopted. H&S experts were purposively sampled. A three-round Delphi study was conducted to identify the factors, and these factors were categorized into 9 main factors developed from a review of the literature and the input of 15 H&S experts, 14 of whom completed all 3 iterations. Stratified sampling was used to gather quantitative data. A total of 257 questionnaires were returned, of which 213 responses were usable for analysis. Exploratory factor analysis (EFA) using Statistical Package for the Social Sciences (SPSS) version 26 was conducted and resulted in 6 main factors. A confirmatory factor analysis (CFA) of structural equation modeling (SEM) was used to establish the validity and reliability of constructs, and finally, path analysis in EQS version 6.4 was used to analyze the results of the questionnaire survey and evaluate the goodness of model fit. The findings were that mutuality, trust, institutional support, project context, and common purpose contribute to CHSA collaboration. Additionally, the influence of project context, common purpose, and CHSA collaboration on H&S performance were found to be statistically significant. The study’s implication is that in order to improve H&S performance, clients, designers, and contractors may not limit the participation of CHSA on the project. The implication for the CI is that by promoting CHSA collaboration, the likelihood of CHSA influence could increase and H&S performance could improve on construction projects. The study revealed that collaboration should be considered for improving H&S performance. The study is limited to respondents who met the selection criteria to participate in the Delphi study and questionnaire survey. Any registered persons who did not receive regular communication and announcements would have not participated. Despite the requirements of the South Africa Construction Regulations 2014 that CHSA should be part of the construction project team, more studies should be conducted to investigate the CHSA level of involvement on the project.