Pomelo fruits (Citrus grandis (L.) Osbeck) contribute to a large segment of fruit production in Vietnam. However, they have been usually consumed as fresh and the development of innovative food products from raw materials such as pomelo fruit has received little attention. Therefore, developing fermented pomelo juice from pomelo fruit might be an ideal option to diversify products derived from pomelo fruit as well as increase the economic value of pomelo fruit. This study aimed to investigate the effects of process parameters on the alcoholic fermentation of pomelo juice including extraction methods, pomelo juice: water ratio, and time of fermentation. The extraction process of pomelo juice by blending assisted with pectinase treatment was found to contribute to better ethanol content (5.15%). The mixture of pomelo juice and water at a 1:1 ratio was observed to effectively facilitate the growth of yeast cells, resulting in the highest yield of ethanol content. The fermentation process was carried out for 2 days to obtain an ethanol content of 5% while it retained the highest vitamin C content (716 ± 23 mg/L) in the fermented pomelo juice. This result can be fundamental in developing fermented juice from pomelo fruit. Further studies on the development of fermented juice from different juice types could be conducted on this approach to create more innovative products from fruit juice.