This study is about determining and evaluating the use of social media applications for marketing purposes across the restaurant industry of the UK. The specific context chosen in this study is small and medium-sized restaurants operating in London because London is the hub of tourists and serves a large number of diverse customers regularly. Small restaurants were selected because these are more vulnerable to external forces of change, especially a crisis such as COVID-19; moreover, these restaurants have limited budgets to develop and use marketing strategies to survive and grow. Overall, the market dynamics for small restaurants (that exist in large numbers across London) are complex and volatile, which makes them an interesting subject to study. An increasing number of customers use smartphones, the internet and social media apps for shopping and buying. Therefore, the intention was to explore and critically evaluate how consumer buying behaviour can be influenced by the marketing practices of restaurants on social media platforms, such as Facebook, Twitter, Instagram, branded applications and WhatsApp. The methodology adopted in this study was qualitative and inductive in nature because the goal was to gather the subjective opinions and perceptions of the managers and owners of small and medium-sized restaurants on their marketing strategies. An interpretivist philosophy was adopted for this study to complement the subjective views of reality. This was suitable because the research objectives required getting the opinions of restaurant respondents as per their unique experiences. Using purposive sampling technique, semi-structured interviews were conducted with 20 respondents who were either owners or managers of small and medium-sized restaurants. Thematic analysis was used to present the analysis and to identify key themes and sub-themes. This study found that social media apps are an effective source of marketing for small and medium-sized restaurants in London. With the help of social media marketing, via apps, restaurants improved their brand visibility and brand image and in some cases sales as well. Friends and family were identified as valuable sources of customer attraction in this regard. Instagram was the most popular and effective social media platform for marketing for the restaurants and for influencing consumer behaviour. Using paid and original content advertisements, improving skills to use social media apps and IT, being more adaptable and proactive towards the business environment, improving social media marketing content and pages and then linking them to websites’ contacts, integration of delivery apps, like Uber Eats, Deliveroo and Just Eat, and willingness to integrate social media marketing strategy are some of the recommendations provided to small and medium-sized restaurants as a result of this study.