Social media has, over the past few decades, become a powerful communication platform capable of influencing consumer decision-making at various levels. The growth of social media has led to the emergence of high profile individuals with huge followings and capability to influence users on critical matters in key topical areas and business sectors. Many tourism and tourism-related business are increasingly using these individuals, known as social media influencers, to attract clients to their establishments. This study aimed to explore the influence of the credibility of social media influencers on the decision-making of domestic tourists in Kenya. It focused on social media influencers and how they affect the decision making of domestic tourists in Kenya to determine whether or not they lead to purchase or non-purchase of holidays within the country. The study targeted domestic tourists who follow social media influencers in Nairobi and Kiambu counties. Questionnaires were used to collect data from a sample of 399 respondents. The study found a moderate relationship between information source credibility and the decision-making of domestic tourists in Kenya. The study further established that social media was a dominant force with profound impact on travel decisions. The study therefore recommends that the tourism sector leverage the use of credible social media influencers in their marketing campaigns. Moreover, tourism marketers and advertisers should incorporate credibility indicators into their marketing assessment processes. Evaluating and monitoring the credibility of information sources should be an integral part of measuring marketing effectiveness.