Ascorbic acid is an antioxidant which promotes increased resistance to infection and acts as preservatives in foods. The complexity and expensive nature of its production led to the search for a relatively simple and cheap method of ascorbic acid production. Hence, this study investigated the potentials of mixed cultures of Aspergillus flavus and A. tamarii for increased ascorbic acid production. Optimization of the fermentation process was carried out at pH (4 – 8), temperature (30 - 45 °C) and agitation speed (60 - 160 rpm) for 96 h. Titration and High Performance Liquid Chromatography techniques were used to determine the quantity of ascorbic acid produced. The highest quantities of ascorbic acid were produced at pH (5.0), temperature (40 °C) and agitation speed of 100 rpm at 96 h of fermentation. The highest quantity of ascorbic acid (9.648 g/L) was produced by the mixed culture compared to acid yield of 6.248 and 7.246 g/L by A. flavus and A. tamarii respectively. The ability of the mixed cultures of A. flavus and A. tamarii in hyper-production of ascorbic acid is therefore established in this study.