The study examined secondary school students' interest in Mathematics as a predictor of their interest in Physics in Otukpo local government area of Benue State, Nigeria. The research was carried out in Otukpo local government area of Benue State, involving a population of 2,374 secondary school (SS) II students, (1453 males and 921 females) offering Physics in some selected secondary schools. A sample of 334 was selected randomly across public secondary schools in Otukpo Local Government Area. Two instruments, Students’ Interest in Mathematics (SIM) and Students’ Interest in Physics (SIP) were validated by three experts from the Department of Science Education and used to collect data. Reliability coefficients of SIM and SIP were 0.83 and 0.89 respectively. The data were analysed using simple regression analysis to address the research questions, while the null hypotheses were tested at the 0.05 level of significance using ANOVA within a multiple regression framework. Findings showed that students’ interest in Mathematics is a predictor of their interest in Physics [F(1, 332) = 27.903, p = 0.000 < 0.05]. Finding also showed that male students’ interest in Mathematics significantly predicts their interest in Physics [F(1, 165) = 30.558, p = 0.000 < 0.05]. However, female students’ interest in Mathematics did not predict their interest in Physics [F(1, 165) = 3.408, p = 0.067 > 0.05]. It was therefore recommended that teachers should guide students to develop interest in mathematics as this could boost their interest in Physics.