The intricate expression patterns and oncogenic attributes of COL11A1 across different cancer types remain largely elusive. This study used several public databases (TCGA, GTEx, and CCLE) to investigate the pan-cancer landscape of COL11A1 expression, its prognostic implications, interplay with the immune microenvironment, and enriched signaling cascades. Concurrently, western blot analyses were performed to verify COL11A1 expression in lung adenocarcinoma (LUAD) cell lines and clinical samples. In addition, COL11A1 knockout cell lines were generated to scrutinize the functional consequences of COL11AI expression on cancer cell behavior by use MTT, colony formation, and scratch wound healing assays. A comprehensive database investigation revealed that COL11A1 was upregulated in a majority of tumor tissues and its expression was highly correlated with a patient's prognosis. Notably, genetic alterations in predominantly occurred as mutations, while its DNA methylation status inversely mirrored gene expression levels across multiple promoter regions. Our findings suggest that COL11A1 helps to modulate the tumor immune landscape and potentially acts through the epithelial-mesenchymal transition (EMT) pathway to exert its oncogenic function. Western blot analyses further substantiated the specific upregulation of COL11A1 in LUAD cell lines and tissues, suggesting a close association with the EMT process. Ablation of COL11A1 in cancer cells significantly reduced their proliferative, clonogenic, and migratory abilities, underscoring the functional significance of COL11A1 in tumor cell behavior. Collectively, this research revealed the prevalent overexpression of COL11A1 in pan-cancer tissues, its profound prognostic and microenvironmental correlations, and the mechanistic underpinnings of its tumor-promoting effects as mediated via EMT signaling. Our findings suggest that COL11A1 could serve as a prognostic and diagnostic biomarker and therapeutic target for cancer.