Citizens in many county governments are not empowered to understand their role in development issues and feel that policy makers do not put into consideration their contribution in major decision making particularly affecting key development programs. Citizens in many counties feel more often than not that their predicaments have not been addressed effectively by their governments, bring in a lot of conflicts which at times has resulted in public unrest. This study therefore focused on establishing an investigation of public participation on policy formulation in devolved governments in Keiyo South Sub County, Elgeyo Marakwet County, Kenya. The objectives of this study were to: establish the contribution of public participation in policy formulation in devolved government of Keiyo South Sub County, Elgeyo Marakwet County, Kenya and to determine the level of public participation on policy formulation in devolved government of Keiyo South Sub County, Elgeyo Marakwet County, Kenya. The study was based on Participatory Communication Theory and Ladder of Citizen Participation Theory. The study used a mixed-method approach, integrating both qualitative and quantitative research. The study adopted a descriptive survey design. The target population was 115 and the researcher obtained a sample size of 89 respondents using Yamane formulae. The study used stratified random sampling to select the respondents. The study used questionnaires and an interview schedule to collect dataThe statistical package for social sciences (SPSS) version 24 was used to analyze quantitative data from the closed-ended questions. Data was analyzed using descriptive and inferential statistics. Descriptive statistics involved frequencies, percentages, standard deviation, and arithmetic mean. Inferential statistics involved correlation and multiple regression. The analyzed data was presented in the form of charts and tables. Privacy was maintained during the entire research period, and participation was entirely voluntary, free from coercion or inducement. The findings demonstrated that respondents agreed with the statement that member’s ideas and contributions in the public participation are given priorities (Mean=3.70, standard deviation=1.40), further, the findings indicated that that the respondents agreed with the statement that there is a moderate level of public participation on policy formulation (Mean=3.73, standard deviation=1.39). The study concluded that significant number of respondents believed in a high level of grassroots participation and others held contrary views, indicating that there may be disparities in how stakeholders perceive the depth of involvement. The study recommended that policy makers and county authorities should take steps to ensure that public participation processes are equitable and inclusive.