This study investigated the effect of blended learning approach on Biology students’ achievement in Ose Local Government Area of Ondo State, Nigeria. The study adopted the pretest-posttest non-equivalent control group research design. The population of this study comprised all the 516 SSS II Biology students in public co-educational schools in Ose Local Government Area of Ondo State. The sample of this study comprised all the 58 students from two intact classes selected. Two research questions were raised and all were hypothesized and tested to guide the direction of the study.