Construction projects play a vital role in the development of any country. The output of the projects is measured in terms of deliverables. However, while executing projects, failures and delays are amid challenges that organizations face, due to the risks associated with the projects. This study aimed to analyse the risk factors related to construction projects of Saudi Arabia. A research model related to internal and external risk factors of project failure is proposed. A total of 76 Saudi’s construction firms were studied. In order to determine the internal consistency of the variables, a reliability analysis technique is applied. The two measures, CR and AVE, are used for convergent tests. To examine the data suitability for factor analysis, we found a value of 0.888 with Bartlett test. In addition, the sphericity has a significance value of 0.00, which indicates that the data relationship is strong and well-suited for factor analysis. A confirmatory factor analysis (CFA) was used to test the validity of the hypothesised constructs. Structural Equation Modelling (SEM) procedures were used to establish the interrelationships between the internal risk factors, external risk factors, and project failure scales and to interpret these scales with respect to their common underlying factors. SEM analysis was also used to examine the mediation impact of nature and COVID-19 on project failure. The results of this study suggest that internal risk factors have a direct, significant, and positive influence on the failure of construction projects in Saudi Arabia. SEM analysis was also used to examine the mediation impact of nature and COVID-19 on project failure. According to the findings of this study, nature and COVID-19 both significantly influence the relationships between internal and external risk factors on construction project failure in Saudi Arabia. The study ended by recommending that further research in this field be expanded outside the Saudi construction market.