Abstract The study investigated the effect of flipped classroom on students' interest and achievement in physics among secondary schools in Ogbia Local Government Area, Bayelsa State. Three research questions guided the study while three null hypotheses were tested at .05 level of significance. Quasi experimental research design was adopted for the study. The population for the study comprised 1564 Senior Secondary School II (SS II) Physics students. The sample size of 326 SS II students from two schools were drawn using simple random sampling. The instrument for data collection was Electromagnetism Achievement Test (EAT) which was developed by the researcher and validated by three experts from the Department of Science Education, Faculty of Education, Federal University Otuoke, Bayelsa State. Kuder- Richardson 20 (K-20) formula was used to estimate the reliability of the instrument and a reliability index of .80 was obtained. Adjusted Mean and standard deviation were used for answering the research questions while Analysis of Covariance (ANCOVA) was used to test the null hypotheses. The findings of the study showed that Physics students taught electromagnetism using flipped classroom had significant mean achieve score when compared to those taught using lecture method. In line with the findings, the researcher recommended among others that Physics teachers should adopt the flipped classroom approach in teaching electromagnetism to enhance students' academic achievement