Purpose: Retailing is one of the fastest-growing sectors in Vietnam. In the sight of foreign investors, the Vietnamese retailing market is very prospective. However, the current competition is very intensive, and retailers are keen on gaining new customers. Hence, Vietnamese retailers have paid more attention to customer loyalty. Saigon Co.op is one of the largest retailers in Vietnam, but its consumers have more choices over a retailer. As a result, Saigon Co.op has realized the significance of customer loyalty. This study aims to determine the factors impacting customer loyalty of Saigon Co.op supermarket in Vietnam. Research design, data and methodology: this study applied the multiple regression analysis with 250 samples collected from Saigon Co.op customers. The questionnaire is provided to respondents via Google Form, and the link is sent to the fan page of Co.op mart on Facebook. Two hundred eighty-seven samples were collected, but 37 samples were removed due to missing values. Exploratory Factor Analysis (EFA) and regression analysis are used for data analysis on SPSS software version 20. Results: The findings show all four determinants of Saigon Co.op's customer loyalty, including Product Quality, Brand Image, Price Strategy and Service Quality. Conclusions: managerial recommendations are provided for supermarkets to improve their customer loyalty in Vietnam and other emerging markets. Limitations and suggestions for further research are also discussed.