The present study sought to establish the influence of parenting styles on adolescent academic achievement in day secondary schools in North Rachuonyo Sub-County, Kenya. Baumrind's theory of parenting style informed the study. The Concurrent Triangulation Design was used. The target population comprised 2409 day secondary students registered for KCSE in 2015 in 47 schools in Rachuonyo North Sub-County. The sample size comprised 263 secondary school students drawn from Sub-County day secondary schools. Ten Principals were randomly selected for interviews. Baumrid's parenting styles questionnaire and interview schedule were used to collect the data from the students and principals respectively. Validity of the questionnaire was ensured by expertise judgement from university lecturers while reliability was determined by internal consistency and reliability coefficient of 0.718 was reported. Quantitative data was analysed using Regression analysis while qualitative data was analysed using Thematic Analysis. The study found that parenting styles statistically significantly predict academic performance of the adolescents, F (4, 242) = 43.529, p < 0.05, R 2 = 0.630. The findings also suggest that independent variables (Authoritative, authoritarian, permissive, neglectful parenting style) explain (63.0%) of the variability of the dependent variable, (adolescents' academic performance). The study recommended that teacher counsellors should identify at risk students from the parents susceptible of negative influence and offer appropriate therapy.