There are significant challenges faced by project managers in Kitui west constituency when it comes to implementing sustainable projects, in particular, the Community Level Infrastructure Development Program was aimed at promoting equitable development across the entire constituency through implementing small scale infrastructure projects. However, there was a partial or no realization of the envisaged benefits. The aim of this study was therefore be to assess the impact on sustainability for Community Development Projects in Kitui West Constituency, Kenya from Participatory Monitoring and Evaluation. The study was based on theory of sustainability, the ladder of participation, stakeholder theory, modern organizational theory and real assessment theory. Research was conducted using a descriptive design for this study. 10 projects that have been operational within 2016 - 2021 was the target population of this study. The researcher targeted 87 respondents comprising of 20 project management committee and 67 constituency development committee members. The study conducted a census of 87 respondents. The study sample size was 10 projects with 87 respondents. For the purpose of collecting data in this study, a questionnaire was used. The study tested the instruments in Kitui central constituency involving 8 respondents. Research instruments were assessed for content, face, and criterion validity. Reliability was measured using Cronbach’s alpha. Data analysis involved descriptive statistics (mean, standard deviation) and inferential statistics (correlation, regression). Results, shown in tables and figures, indicated that community engagement, capacity building, resource use, and communication positively impacted project sustainability. The study concludes that involving community members in project planning, implementation, and evaluation fosters ownership and empowerment. The study recommends that the constituency should involve community members in the planning and decision-making processes is crucial which can be achieved through community meetings, workshops, and focus group discussions where residents can voice their needs, priorities, and ideas.