The purpose of the study was to assess the role of volunteerism as a parental involvement strategy in the achievement of core competencies among learners in public primary schools in Nandi County, Kenya. The study was guided by Joyce Epstein’s Model of parental involvement. The sample size comprised 293 participants who included 6 sub-county education officers, 24 head teachers, and 263 parents. Multistage sampling was used to determine the schools to take part in the study. The study adopted multistage sampling. The research instruments used in collecting data were questionnaires for parents and interview schedules for Sub-County education officers and head teachers. Validity was tested through factor analysis, while the Crobanch Alpha was used to measure the internal consistency of the questionnaire. Quantitative data was analysed using descriptive and inferential statistics and presented in the form of figures and tables. Qualitative data was analysed using thematic analysis. The study results showed that volunteerism as a parental involvement strategy had a positive linear effect on the achievement of core competencies among learners in public primary schools (β=0.432, p=0.000). The role of parental volunteerism is invaluable in creating a supportive and enriching educational environment in public primary schools. The study recommends that the schools' management boards establish structured programs that promote and recognize parental volunteerism, fostering a collaborative environment that enhances students' academic journey.