The lncRNA MIR4435-2HG was highly expressed in lung cancer tissues and correlated with histological grades and lymph node metastasis. Phenotypic analysis indicated that MIR4435-2HG knockdown inhibited lung cancer cell proliferation and invasion in vitro and in vivo. Notably, MIR4435-2HG knockdown suppressed the EMT (epithelial-mesenchymal transition) process and cancer stem cell traits of lung cancer cells. Mechanistically, MIR4435-2HG knockdown decreased the transactivation of B-catenin. MIR4435-2HG interacted with B-catenin and thus prevented its degradation by the proteasome system. High expression of lncRNA MIR4435-2HG correlates with lung cancer progression MIR4435-2HG promotes lung cancer cells proliferation and invasion MIR4435-2HG knockdown suppresses the EMT process and cancer stem cell traits MIR4435-2HG knockdown inhibits the B-catenin signalling. Kaplan-Meier analysis of the 52 patients with lung cancer revealed that high MIR4435-2HG expression in lung cancer tissues was significantly correlated with a reduction in overall survival.