This study examined gender as a predictor of Physics students’ academic performance in Senior Secondary School external examinations in Ado Local Government Area of Ekiti State, Nigeria. An ex-post-facto research was employed for the study. The entire Physics students in Ado-Ekiti that sat for the West African Examination Council (WAEC) external Examination between 2017 to 2019, were used for the study. A total of three hundred candidates (300) were randomly selected as a sample from five (5) senior secondary schools for the study. Frequency and t-test were used to test the four formulated null hypotheses. The result indicated that; there was a significant difference in the academic performance of male and female Physics students in mixed senior secondary schools, also there was a significant difference in academic performance of male and female Physics students in single-sex senior secondary school, similarly, there was a significant difference in academic performance of female students in Physics in single-sex and mixed senior secondary schools. There was a significant difference in academic performance of male students in Physics in single-sex and mixed senior secondary schools. Based on the findings, appropriate conclusions and recommendations were made.