N7-methylguanosine (m⁷G) modification occurs at the 5’ cap of mRNA in eukaryotes, and is also found at specific sites on tRNA and rRNA, showing wide conservation across various biological organisms. Aberrant m⁷G modification is involved in the dysregulation of gene expression and serves as a biomarker for multiple cancers, with significant potential for applications in tumor diagnosis and therapy. This review summarizes the biological functions and regulatory mechanisms of m⁷G modification, and outlines its potential clinical applications. It also highlights the oncogenic roles of aberrant m⁷G modification and its association with prognosis, providing a detailed discussion of the role and molecular mechanisms of abnormal m⁷G modification in regulating drug resistance in various cancers.