Citric acid production is important at an industrial level because flavored most of the food products. In the present century, the re-use of agro-industrial waste products has become very important, nonetheless in Mexico, a high amount of agricultural residues is discarded, among which are non-marketed such as mango fruits. The mango fruit is an important income for families that sustain themselves from this crop and contains viable amounts of fiber, carbohydrates, ash, and carotenes, among others. Thus the objective of this work was to evaluate the production of citric acid using the mango peel of six commercial varieties from southern Chiapas, as a substrate in fermentation, using Penicillium spp. During fermentation, a reduction in the pH value was observed in all treatments below 5.0 and Brix degrees less than 2.0. Two points of maximum acidity were observed in the growing medium, on day 3 with the manila, criollo, and tomy varieties, and on day 6, the rest of the treatments. The maximum concentration of soluble protein was found with the ataúlfo variety and the maximum concentration of citric acid obtained was found with the ataúlfo variety. The mango fruit peel could be a substrate with potential use for citric acid production.