Using mixed quantitative and qualitative methods, the current study examined the efficacy of fully online flipped classroom. 250 Chinese undergraduate social work students, with 126 students experienced the conventional online teaching method and 124 students learned with the online flipped classroom approach, were involved. The quantitative analyses show that students who experienced online flipped classroom had a lower performance in lecture participation and overall course grade; and had less positive perceptions of the course. The qualitative analyses reveal both advantages and challenges of the online flipped model. There is insufficient evidence to conclude the effectiveness of online flipped classroom in social work education and further investigation on cultural and contextual factors contributing to an effective online flipped approach is warranted.