Efficient implementation of policies has a crucial function in improving service delivery in the public and private domains. The success of policy execution directly impacts how much the policy contributes to enhancing service delivery. To achieve high-quality, efficient, and timely service delivery, the Directorate has adopted a strategy of revamping, retooling, and continuous learning. The Office of the Director of Public Prosecutions (ODPP) follows the Excellence Charter and adheres to the ODPP Strategic Commitments for the period 2020-2023. In this context, the researcher focused on examining the impact of human resource policy implementation on service delivery at the Office of the Director of Public Prosecutions, Western Region, Kenya. Implementation Theory and Organizational Culture Theory guided the study. Descriptive research design was utilized. The target population was 198 individuals working within the ODPP Western Region of Kenya. Individual respondents were selected randomly from Legal, Administration, and Support Staff in region. Data collection was done through questionnaires distributed to staff and document analysis was conducted in the resource centres available in the region. Face-to-face interviews with selected County Heads were carried out by the researcher. Descriptive statistics, such as means, percentages, and frequencies, was used in the research's quantitative and qualitative approaches to analyze the data using SPSS. The findings indicated that human resource has a significant impact on service delivery at the ODPP, Western Region, Kenya. The results upon Analysis of Variance (ANOVA) established human resource policy implementation had an r of 0.265, β = 0.252, t= 3.786, p= 0.05. It was concluded that Policy Implementation had a statistically significant impact on service delivery in the ODPP. The study recommends that ODPP should enhance HR policy implementation and service delivery in the Western Region by improving communication, offering regular training, fostering open dialogue, establishing a robust monitoring framework, deploying dedicated HR Officers, and ensuring transparent and unbiased career progression and training opportunities. The study will be part of references materials for all ODPP Staff, stakeholders, policy makers and other institutions in Kenya as an insightful tool in advancement of efficacy and efficiency in policy implementation.