This study examined impact of principals? leadership styles on teaching and learning in secondary schools in Ilorin metropolis, Kwara State. Six objectives were formulated for the purpose of this study to determine the impact of principal?s situational leadership style on teaching and learning in secondary schools in Ilorin Metroplis, Kwara State, to ascertain the impact of principal?s transactional leadership style on teaching and learning in secondary schools in Ilorin Metroplis, Kwara State, Also, six research questions were raised and answered while six null hypotheses were generated and tested at 0.05 significance level. Literatures were reviewed according to the variables in the objectives of the study. Descriptive survey design research was employed in the analysis. The population of the study was 1736 respondents which consist of 51 senior public secondary schools principals, 1647 teachers and 38 officials of M.O.E. A sample of 254 respondents (16 principals, 206 teachers and 32 officials of Ministry of Education) was selected through the simple random sampling technique. Data for the study were collected through a self-structured questionnaire titled "Impact of Principals? Leadership Styles on Teaching and Learning" (IPLSTL). Pilot study was conducted in four schools and the Cronbach?s Alpha was used to determine a reliability coefficient index of 0.88. The data generated were analyzed using frequency counts, percentages, mean score and the Analysis of Variance (ANOVA.) The findings of the study revealed that situational, transactional, transformational, democratic and charismatic leadership styles had positive impact on teaching and learning while autocratic leadership style had a negative impact on teaching and learning in secondary schools in Ilorin metropolis. This was evident from the findings which concluded that teaching and learning outcomes were impacted significantly by the six leadership styles depending probably on the prevailing circumstances in the schools. Based on the findings of the study, it was recommended, among others, that Principals should adopt situational leadership style to eliminate predictable leadership approach in their administration of schools which affects teaching and learning outcomes. Principals should not use the autocratic leadership style except when the need arises to exert authority and quell disciplinary problems which mostly undermine teachers? classroom performance that affects teaching and learning outcomes.