In the construction industry, ensuring high-quality standards is a critical aspect of construction projects and plays a pivotal role in the sustained viability and triumph of contemporary construction companies. However, existing literature highlights the persistently subpar levels of project quality within the construction sector. This situation is manifested through cost overruns, time delays, deficient project definition, and fluctuations in project scope, which are indicative of insufficient project risk management practices. Although several studies have examined project risk management practices, little emphasis has been placed on evaluating their impact on quality in the construction industry. Hence, this study examined the dimensional effect of optimal project risk management practices on project quality of selected construction companies in Nigeria. Survey research design was adopted. The population was 202 top management and mechanical department staff of three selected construction companies in Lagos State, Rivers State, and the Federal Capital Territory of Abuja, Nigeria. A sample size of 176 was found to be usable. A validated questionnaire was adopted for data collection. Cronbach’s alpha reliability coefficients for the constructs ranged from 0.74 to 0.98. The response rate was 87.1%. Data were analyzed using the Smart partial least squares structural equation modeling (PLS-SEM) software, which allowed for the testing of path analysis and hypotheses. A confirmatory factor analysis (CFA) was employed to assess the factor loading of the variables. Findings indicated that project risk management practices had significant effect on project quality of selected construction companies in Nigeria (Adj R2 = 0.54, F2 = 0.058, Q2 = 0.507, p < 0.05). The study concluded that project risk management practices improved the quality of the selected construction companies in Nigeria. The study recommended that project managers should establish and implement effective quality management systems that outline clear processes and procedures for ensuring project quality. Develop quality control plans that include inspection, testing, and monitoring activities throughout the project lifecycle. Incorporate quality management standards and best practices, such as ISO 9001, to enhance quality assurance processes.