Objective: Irisin is an exercise-induced myokine known to induce adipocyte browning through induction of uncoupling protein 1. The membrane protein FNDC5 is known as the precursor of irisin. Recent studies have reported that irisin is also an adipokine. However, there is limiting evidence on the role of endogenous irisin from adipocytes. In this study we aim to elucidate the effects of FNDC5 overexpression and silencing on adipogenesis and the mechanisms involved. Methods: Recombinant irisin, plasmid expressing FNDC5, and small interfering RNA were utilized to observe the effect on adipogenesis. Gene expressions were measured by real-time PCR while protein expressions were analyzed by Western blot. ELISA was performed to measure the irisin secretion during adipocyte differentiation. To observe the effect of irisin on lipid accumulation, Oil Red O staining was performed at day 8 after adipocyte differentiation. Results: Our results show that the gene expression of irisin precursor FNDC5 and irisin secretion is increased at the early stage of adipogenesis. Both recombinant irisin treated cells and FNDC5-overexpressed cells resulted in inhibition of adipogenesis, evidenced by downregulation of C/EBPα, PPARγ, and FABP4 expression and reduced lipid accumulation. Further data showed that the inhibitory effect of irisin on adipogenesis is mediated though potentiation of Wnt expression, which is known to determine the fate of mesenchymal stem cells and regulate adipogenesis. Conversely, FNDC5 knockdown cells showed downregulated Wnt expression, but failed to further induce adipogenesis. Conclusion: This study suggests that both exogenous and endogenous irisin is able to inhibit adipogenesis and that activation of Wnt and subsequent repression of transcription factors is partly involved in this process.