Since clinical drugs need to be approved for their liver metabolism efficiency before commercialization, a powerful in vitro drug-screening platform is imperative and indispensable for the clinical medicine and pharmaceutical industries. An essential issue in the development of drug screening platforms is choosing cell candidates that mimic and perform cell/tissue functions of normal hepatic tissues in vivo. In this study, we developed a self-designed bioreactor system to provide and mimic an appropriate environment for systematic cell expansion, micro-tissue formation, and increased cellular cytochrome P450 (CYP) enzymatic activities. Since CYP3A4 is the most plentiful and crucial enzyme in drug metabolism among liver CYP superfamily members, we demonstrated that micro-tissue formation under three-dimensional dynamic conditions could enhance cellular CYP3A4 enzymatic activity, maintain cell viability, and preserve adhesive abilities. Furthermore, Ca-alginate scaffolds used in this study can be completely removed by a non-toxic chelating reagent (EDTA solution), and the functional micro-tissues can be collected by slow-speed centrifugation. In conclusion, these micro-tissues are advantageous and show great potential in in vitro drug metabolizing assays.