Gallbladder carcinoma (GC) is an extremely malignant gastrointestinal tumor, but relevant mechanisms are still under investigation. MicroRNA (miR) is differentially expressed in a variety of tumors. Here we explored miR-204 in patients with GC and related mechanisms. A GSE104165 chip was downloaded from the gene expression omnibus (GEO) for analysis. The qRT-PCR assay was used for quantifying miR-204 and Notch2 in the serum and tissues of the patients, and the patients were followed up for 3 years to analyze independent factors of prognosis. The CCK8, transwell, and flow cytometry assays were applied for analyzing proliferation, invasion, as well as apoptosis of cells, and the dual luciferase reporter (DLR) assay was adopted for determining the association of miR-204 with Notch2. MiR-204 was low in patients with GC, and it might serve as a diagnostic indicator for GC. In addition, patients with low e MiR-204 usually faced high rates of III+IV stage, distant metastasis, and low differentiation, and also showed a poor prognosis. DLR assay verified the targeted binding of miR-204 to Notch2 mRNA.