Abstract: Frozen foods play an important role in both economic and business aspects of Thailand. For decades, frozen foods have been promoted as a major source of Thailand's income. In addition, a number of people who work outside have less time to cook food for each meal. The demand of frozen food products increases rapidly among the changing society in Thailand. Thus, this study attempted to find factors influencing consumer decision-making process of Thai frozen food products in order to develop ways in which Thai frozen foods can meet consumer needs and become competitive in the global market. The purposes of this study were to analyse the consumer decision-making process of Thai frozen foods to analyse the marketing mix of 4Ps: product, price, place and promotion influencing the consumer decision-making process of Thai frozen foods and to find the relationship between the marketing mix of 4Ps and the consumer decision-making process: need recognition, prepurchase search, evaluation of alternatives, purchase and postpurchase evaluation. As the result, in the overall aspect of each marketing mix, the factor that the consumers considered primarily buying decision was product whereas the other factors that the consumers used in buying decision were promotion, place and price, respectively. The study's results found that the sales promotions of frozen foods influenced consumers' need recognition. The fair prices for quantity, the various distribution channels, the reachable advertising and publicity in various media and the overall aspect of promotion influenced prepurchase search. The overall aspect of product and the reputation of brand influenced evaluation of alternatives. The reachable advertising and publicity in various media and the overall aspect of price influenced purchase behavior. Finally, the fair prices for quality influenced postpurchase evaluation.