Gastric cancer (GC) is the third leading cause of cancer-related mortality in China and worlwide; hence, the identification of GC-related genes is necessary for the development of effective treatment strategies. In this study, histone deacetylase 3 (HDAC3) was identified as the most significantly upregulated cancer-related gene in GC tissues by microarray. In accordance with this, HDAC3 expression was found to be upregulated in GC cell lines/tissues. Further experiments indicated that the knockdown of HDAC3 decreased GC cell viability, reduced the colony formation number and decreased tumor weight. To explore the underlying mechanisms, the overexpression of HDAC3 was induced by transfection with an overexpression plasmid, followed by miRNA microarray, and we identified miR-454 as the most markedly upregulated miRNA. Accordingly, miR-454 expression was upregulated in GC cell lines/tissues and a high level of miR-454 indicated a high HDAC3 expression in GC tissues, and miR-454 knockdown reduced cell viability. In addition, a high level of miR-454 was significantly associated with an advanced clinical stage, lymph node metastases and a poor prognosis of patients with GC. Furthermore, CHD5 was identified as a direct target of miR-454. CHD5 was downregulated in GC tissues/cell lines and the expresssion of CHD5 inversely correlated with the level of miR-454 in GC tissues. Taken together, these observations indicate that HDAC3 is associated with GC cell growth via the miR-454-mediated targeting of CHD5.