Digital transformation has accelerated the adoption of green marketing practices, with brands increasingly using eco-friendly messages, visuals, and narratives across social media platforms. As consumers, especially youth, navigate these digital spaces, a new behavioural phenomenon is emerging, Eco-FOMO (Fear of Missing Out on Eco-friendly Choices). Eco-FOMO reflects the anxiety individuals feel when they perceive others adopting more environmentally responsible lifestyles, participating in sustainability challenges, or purchasing green products. Despite its rising relevance, Eco-FOMO has received little academic attention and remains theoretically underexplored. This conceptual paper introduces Eco-FOMO as a distinct psychological construct shaped by social comparison and digital influence. It examines how green digital marketing cues such as eco-labels, carbon-neutral claims, green influencer posts, and sustainability campaigns can trigger Eco-FOMO among consumers. The paper further proposes that Eco-FOMO can positively influence sustainable consumer engagement, including intentions to choose eco-friendly products, willingness to pay for greener alternatives, and participation in environmental initiatives.

A conceptual framework is presented to explain the relationship between green digital marketing, Eco-FOMO, and sustainable engagement, supported by mediators such as green identity activation and perceived environmental responsibility, and moderators like environmental awareness and social influence. This framework contributes to the understanding of how digital communication shapes sustainable behaviour in the modern era.