This study was conducted for the purpose of maintaining the sustainable loyalty of customers towards modern retail channel in the context of the Covid-19 pandemic. The data used in the study were collected from 215 customers who went shopping at convenience stores, mini-marts and others made purchase by means of online shopping via the supermarkets' websites during the Covid-19 pandemic in Vietnam. The result shows that there are five (5) factors positively affecting customers' loyalty including perceived value, trust, service quality, personality traits, and commitment, among which perceived value has the strongest impact on customer loyalty. In addition, the study also shows that the switching cost factor moderates the relationship between customer trust and loyalty. Based on the result, the study proposes a number of managerial implications for the managers of modern retail channel from which to have suitable business methods and marketing strategies to meet the requirements of different types of customers, thereby increasing customer loyalty, gaining competitive advantage, and bringing sustainable business performance to businesses during the new normal and post-pandemic period.