The study examined the relationship between teachers’ characteristics and students’ academic performance in Lagos State senior secondary schools, Nigeria. Two research questions were raised to guide the study and two null hypotheses were tested at 0.05 level of significance. The study was anchored on the Theory of Educational Effectiveness. Descriptive survey of correlational designs was adopted. The study population comprised 8,865 teachers and all SSS 3 students in the 327 Lagos State senior secondary school students, Nigeria. Simple random sampling technique was adopted to generate the sample size of 351 teachers and SSS 3 students in Lagos State senior secondary school. Two research instruments were used to collect data, titled: Teachers’ Characteristics Questionnaire (TCQ) responded to by teachers and Records Observation Format (ROF) of SSS 3 students WASSCE in Lagos State. The instrument reliability was subjected to test-retest method using Pearson’s Product-Moment Correlation Coefficient Analysis at 0.72 and 0.74. The data collected were analysed using the Pearson’s Product-Moment Correlation Coefficient Analysis with the aid of Statistical Package for Social Science (SPSS) Version 26.0. The test of the first and second hypotheses showed that a positive, strong and significant relationship existed between teacher professional experience and students’ academic performance in Lagos State senior secondary schools, Nigeria (r = .59, ρ < 0.05); and a positive, strong and significant relationship existed between teachers’ characteristics and students’ academic performance in Lagos State senior secondary schools, Nigeria (r = .62, ρ < 0.05). The study concluded that teachers’ characteristics contributes positively to students’ academic performance in Lagos State public public senior secondary schools, Nigeria. The study therefore, recommended that teachers’ characteristics such as experience significantly contributed to students’ academic performance in Lagos State senior secondary school.