This study examines the influence of ecotourism on tourist behavior in Greece, focusing on sustainability awareness as a key factor in decision-making and the impact of marketing strategies on tourists’ willingness to choose Greece as an ecotourism destination. A quantitative approach was used, collecting data from a convenient sample of 380 respondents through structured, face-to-face questionnaires administered to international tourists who self-identified as ecotourists traveling to Athens International Airport as their destination. Multiple regression analysis revealed that sustainability awareness significantly predicts tourists’ choice of Greece for ecotourism, while personalization of experiences also plays a positive role. Additionally, correlation analysis indicated that marketing strategies, such as eco-labels and social media campaigns, have a strong influence on tourists’ destination decisions. The study highlights the importance of sustainability and targeted marketing in shaping ecotourism behavior, offering insights for enhancing Greece’s position as a leading ecotourism destination.