Immature colon carcinoma transcript-1 (ICT1) is a newly identified oncogene, which regulates mobility, apoptosis, cell cycle progression and proliferation of cancer cells. Nevertheless, the role of ICT1 and its clinical significance in gastric cancer (GC) is largely uncovered. Here, we found that ICT1 displayed higher expression in GC tissues compared to corresponding tumor-adjacent tissues. Further investigation confirmed ICT1 overexpression in GC cell lines. Clinical data disclosed that high ICT1 expression correlated with distant metastasis and advanced tumor-node-metastasis (TNM) stage. The Cancer Genome Atlas (TCGA) data further demonstrated that GC tissues with metastasis showed a significant higher level of ICT1 compared to those without metastasis. Furthermore, ICT1 overexpression notably predicted poor prognosis of GC patients. Functionally, we demonstrated that ICT1 knockdown suppressed invasion and migration of MGC-803 and BGC-823 cells in vitro. ICT1 overexpression promoted the mobility of SGC-7901 cells. Mechanistically, microRNA-205 (miR-205) was recognized as a direct down-regulator and inversely modulated ICT1 abundance in GC cells. miR-205 expression was down-regulated and negatively associated with ICT1 level in GC tissues. Underexpression of miR-205 indicated an obvious shorter survival of GC patients. miR-205 overexpression inhibited migration and invasion of MGC-803 cells, while these inhibitory effects were reversed by ICT1 restoration. Taken together, we have the earliest evidence that miR-205 regulation of ICT1 functions as an oncogene and prognostic biomarker in GC.