Transforming growth factor β regulator 4 (TBRG4) is upregulated in lung cancer, but its biological role and underlying mechanisms remain poorly understood. In this study, we analyzed pancancer gene expression profiles and clinical data from University of California, Santa Cruz Xena (UCSC Xena) to evaluate the prognostic significance of TBRG4 using univariate and multivariate Cox regression analyses. Genes with a Pearson correlation coefficient above 0.4 with TBRG4 in lung cancer were identified via UALCAN, followed by pathway enrichment analyses to explore their functional associations. To investigate TBRG4's role in lung cancer progression, we assessed cell proliferation, colony formation, and cell cycle alterations in lung cancer cells following TBRG4 knockdown. Western blot analysis was performed to examine the effects of TBRG4 depletion on key cell cycle regulators and epithelial-mesenchymal transition (EMT) markers. Additionally, the biological significance of TBRG4 was evaluated in vivo using a mouse xenograft model. TBRG4 knockdown significantly inhibited cell proliferation and colony formation while inducing cell cycle arrest and apoptosis in lung cancer cells. Analysis of co-expressed genes in the The Cancer Genome Atlas - Lung Adenocarcinoma (TCGA-LUAD) cohort revealed enrichment in cell cycle-related pathways, aligning with our experimental findings. Furthermore, TBRG4 depletion reduced EMT marker expression and suppressed tumor growth in vivo. Collectively, these findings suggest that TBRG4 may serve as a promising prognostic biomarker and therapeutic target in lung cancer.