Aflatoxin B 1 (AFB 1) contamination in foods is an important health challenge for low-and middle-income countries in subtropical regions. AFB 1 has been detected in a variety of foodsin Guangzhou, while the risk of dietary exposure is unknown. This study aimed to assess the probabilistic risk of dietary exposure to AFB 1 contamination in food stuffs in Guangzhou by using margin of exposure (MOE) and quantitative liver cancer risk approaches. A total of1854 AFB 1-contaminated foodstuffs were sampled in supermarkets, agricultural markets, retail shops, and family workshops from 11 districts of Guangzhou, and AFB 1 content was determined by HPLC-fluorescence detector. In total, 9.9% (184/1854) of the test samples had AFB 1 concentrations above the limit of detection. Home-made peanut oil had the highest AFB 1 concentration, with a mean value of 38.74 ± 47.45 μg kg −1. The average MOE levels of Guangzhou residents ranged from 100 to 1000. The risk of liver cancer was 0.0264 cancers (100,000 population year) −1. The health risks of suburban people were higher than those of urban people, and home-made peanut oil was the main contributorto dietary exposure to AFB 1 among suburban residents in Guangzhou. The production of home-made peanut oil should be supervised to reduce the risk of AFB 1 exposure.