Across the globe, studies have shown that the number of projects that are considered challenged or failed is significantly higher than those deemed successful. Further, in an ever intensively competitive market due to digital disruption, organizations are keen to implement projects successfully to avoid wastage of limited capital. The purpose of this study was to establish the influence of project management maturity on project implementation in the large peer group financial institutions in Kenya. The objectives of the study were: to establish the extent to which organizational structure influences project implementation in the large peer group financial institutions in Kenya; to examine the influence of organizational project processes on project implementation in the large peer group financial institutions in Kenya; to assess the influence of people management on project implementation in the large peer group financial institutions in Kenya and to determine the influence of systems and tools on project implementation in the large peer group financial institutions in Kenya. The study is grounded on two theories namely, The Systems Theory and Theory of Constraints. The quantitative cross-sectional survey research design was used to enable the researcher to obtain opinions of project management professionals in large peer group financial institutions regulated by the Central Bank of Kenya. The study used a sample of 123 project management professionals derived from a target population of 178. The sample size was derived at using stratified sampling. A questionnaire was distributed to collect data from the potential respondents. The data collected were analysed using descriptive statistical tools and inferential tools. The Chi-Square test of association was employed to test the study hypothesis. The findings were presented in the form of tables and figures. The study findings suggested that project management maturity has a significant influence on project performance in the large peer group financial institutions in Kenya. Further, findings revealed that an appropriate organizational structure, adequate people management, the use of project management processes and the deployment of appropriate technology influenced project performance in the large peer group financial institutions. Based on the findings the following recommendations were made; Senior executives in the large peer group financial organizations should focus on the project management function by having it appropriately embedded in the organization structure given its strategic importance; the organization should ensure the project management function is sufficiently resourced from a staff and technology perspective. Follow up studies should examine the influence of project management maturity in the medium and small peer group financial institutions. Also, it would be worth exploring the influence of the respective maturity levels and the use of maturity models on project implementation.