Over the last decade, digital marketing and technology have gradually penetrated the food and beverage industry, redefining its marketing mix. However, the urgency caused by the COVID-19 pandemic spurred the digital transformation of the industry, as businesses were forced to adapt to many changes and restrictions, reshape their operational models, and find ways to survive in an unstable marketplace. The purpose of this paper is to examine the transformation of the marketing mix in the food and beverage service supply chain due to the emergence of digital marketing. To this end, critical success factors for the digital transformation of the food and beverage service supply chain were identified based on the literature. These factors were assessed by experts from the Greek market using a grey decision-making trial and evaluation laboratory (DEMATEL) approach because of the complexity and interdependence of the factors interfering in the decision-making process. After a screening process, eight experts were selected to participate based on their experience and their acknowledged presence in the sector. DEMATEL is a multi-criterion decision-making method used to assist in addressing practical assessment issues. Its main advantage is that it can detect and observe the interdependence among the primary components and their relevance in the decision-making process. Additionally, it facilitates the visual display of the results, assisting in the analysis of the causal influence of factors. The combination of DEMATEL with grey system theory is useful because it makes it easier to analyze ambiguities brought on by uncertainties, lack of knowledge, or inadequate human actions. Fourteen critical success factors were identified, and they were grouped into three broad categories: technology-driven, consumer-driven, and industry-driven. Seven factors were classified as causes, and seven factors were classified as effects. In addition, with the use of the DEMATEL approach, the factors were grouped into core, driving, independent, and prominent factors.