The ISO 9001 standard is the most widespread standard in the world that sets requirements for a quality management system. Thousands of companies around the world have implemented the quality management system according to ISO 9001, and there are many reasons why they decided to implement this management system in their companies. The main goal of this paper is to determine the impact of the introduction of a quality management system according to the ISO 9001 standard on the performance of a selected sample of transport companies after its successful implementation as a strategic step to achieve better competitiveness. The impact of the introduction of the quality management system on the performance of a selected sample of 17 transport companies was investigated through the use of financial analysis, regression, and correlation analysis tools. The first significant finding was that the selected investigated indicators, such as profitability of assets, profitability of sales, size of the transport company, and age of the transport company in the selected transport companies, showed a significant positive difference in their average values in the period after obtaining ISO 9001 certification when compared to the period without certification. Further investigation of the financial situation in transport companies that already had a quality management system in place according to the ISO 9001 standard revealed that all the values of the selected indicators acquired positive values in 2020 during the COVID-19 pandemic, which could also be due to the fact that transport companies kept their customers.