Mental health is an important developmental aspect of any society. This study sought to assess the effect of the county legal framework on the implementation of mental health programmes in Nakuru County. The study was guided by the General Systems Theory. A descriptive survey design was used which involved a mixed-methods approach. The target population was the 80 respondents who are directly associated with the implementation of mental health programmes in Nakuru County. Due to the small population, a census procedure was utilized. Primary data was collected through the use of a questionnaire and interview guide. Quantitative data was analyzed through the SPSS software (v25). Descriptive statistics were analyzed through the use of frequencies and percentages while inferential statistics were analyzed through the Pearson Correlation and linear regression analysis and the findings were presented in form of tables. The qualitative data were analyzed thematically and presented through narratives. The study found that the county legal framework had a positive relationship with the implementation of mental health programmes in Nakuru County, Kenya (r=0.428; p=0.000). The county legal framework positively and significantly affected the implementation of mental health programmes in Nakuru County, Kenya. Also, improving the county's legal framework would have a positive impact on the implementation of mental health programmes in Nakuru County, Kenya. This study recommends that a study should be conducted on the implementation of mental health programmes focusing on the service-users of mental health services and programmes in county governments in Kenya. It is hoped that the findings of this study will increase awareness of mental health services in the county as well as help policymakers formulate effective policies and strategies on mental health programmes, services and public service delivery in Nakuru County.