The proficiencies of Flipped classroom instructional approaches on students’ achievement and retention in office practice was established. Anon-equivalent groups quasi experimental research design was used for the study with a sample size of 69 students. Achievement and retention of students in Office practice were measured using office Practice Achievement Test (OPAT). Using Kuder-Richardson 20 (K-R20) formula, the internal consistency reliability coefficient of OPAT was calculated at 0.89. The test re-test method was used to assess the reliability coefficient of OPAT at 0.91 The data were analyzed using mean and standard deviation while analysis of covariance (ANCOVA) was used to test the hypotheses at 0.05 level of significance. The study found that the flipped classroom instructional approaches enhanced students’ achievement and retention in office practice. Based on the findings of the study, it was recommended that vocational educators should adopt flipped classroom instructional approach for teaching office practice and other related vocational courses.