Epidermal growth factor receptor (EGFR) status is the major determinant of non-small cell lung cancer (NSCLC) therapy selection. Studies have hinted that EGFR antibodies or tyrosine kinase inhibitors were beneficial in patients with EGFR mutation-negative but EGFR-overexpressing of NSCLC. However, the mechanisms underlying EGFR amplification and overexpression in NSCLC remain largely unknown. Here, we report that rs884225, a single nucleotide polymorphism in the EGFR 3'-terminal untranslated region, was significantly associated with EGFR expression level and contributed to NSCLC susceptibility. Mechanistically, the rs884225 C allele enhanced EGFR expression by altering the miR-103a-3p binding site, thus impairing miR-103a-3p's anti-tumourigenic function. As a tumour suppressor gene, miR-103a-3p expression correlated with overall and recurrence-free survival in NSCLC patients. Furthermore, miR-103a-3p inhibited growth and metastasis via effects on the KRAS pathway and epithelial-to-mesenchymal transition in EGFR wild-type NSCLC cell lines, respectively, which substantially reduced EGFR expression and activity. Thus, rs884225 may be a biomarker for NSCLC susceptibility, and miR-103a-3p may be a potential therapeutic target in NSCLC.