Abstract: High intake of ultra-processed foods (UPFs) is closely associated with obesity in epidemiological studies, and obesity is a known risk factor for at least 13 types of cancer. Moreover, food additives in UPFs (such as emulsifiers), migration of packaging materials, and nutritional imbalance may directly promote tumorigenesis through inflammatory and gut microbiota dysbiosis pathways. Recent cohort studies have shown that UPFs intake is positively correlated with overall cancer incidence and the risks of specific cancers such as breast and colorectal cancer; however, results are heterogeneous, and most associations require further verification. This reviewsummarizes the epidemiological evidence on the association between UPFs and cancer risk, analyzes potential mechanisms, and provides a scientific basis for risk-based regulatory policies to reduce population exposure.