MicroRNAs are reported to be involved in tumor development. This study aims to investigate the biological functions and molecular mechanisms of microRNA-19a-3p in gastric cancer cells. TCGA-based expression analysis and qRT-PCR assay illustrated that microRNA-19a-3p was overexpressed in gastric cancer. MTT and Transwell assays indicated that microRNA-19a-3p could strengthen the proliferation, migration, and invasion of gastric cancer cells. SMOC2 was bioinformatically predicted as the target of microRNA-19a-3p, followed by identified using a dual-luciferase assay. The effects of microRNA-19a-3p/SMOC2 regulatory axis on gastric cancer cells were examined by MTT and Transwell assays as well. Concludingly, this study demonstrated that microRNA-19a-3p could promote the aggressive cell phenotypes of gastric cancer cells by targeting SMOC2.