This study investigates the effectiveness of social media influencers in promoting eco-friendly hotels within the Greek tourism sector, focusing on the impact of influencers on consumer perceptions and behaviors. Using a mixed-method approach, the research involved a survey of a convenient sample of 157 participants from various age groups, examining the role of influencers in shaping decisions related to eco-friendly accommodations. Results indicate that younger consumers (ages 18–24) engage more frequently with social media influencers but place less importance on sustainability compared to older participants (aged 45 and above), who prioritize environmental responsibility in their travel choices. The study highlights the need for targeted marketing strategies, with younger audiences being more influenced by engaging visual content, while older consumers respond to genuine sustainability practices. Additionally, the research identifies challenges such as greenwashing, which can undermine trust between influencers and their audiences. Authenticity and transparency are found to be crucial for the success of influencer marketing in promoting eco-friendly hotels. This paper contributes to the growing body of literature on sustainable tourism marketing and suggests directions for future research, particularly regarding the ethical implications of greenwashing and the long-term impact of influencer-driven sustainability efforts.