<p>The successful diffusion of novel, sustainable products represents a central challenge in management and marketing strategy. Dominant theoretical frameworks, such as the Theory of Planned Behaviour, often conceptualise consumer acceptance as a static, rational decision, failing to capture the dynamic, multi-stage journey of adoption. This study develops a comprehensive, dynamic model to address this gap. Through a systematic review of the consumer acceptance process for a challenging novel food—seaweed—this study reframes adoption using the Stages of Change model. The article elaborates four distinct stages and demonstrates that the influence of key determinants (e.g., cognitive, affective, and control factors) shifts decisively across this journey. This is the first study to apply and extend the Stages of Change framework to novel product adoption. This research moves beyond our specific empirical context to offer a generalisable theoretical framework that helps explain the adoption of other sustainable innovations (e.g., insect protein, cultured meat). While grounded in the context of seaweed, this model offers insights for managing the adoption of diverse innovations, such as electric vehicles or biodegradable packaging, where unfamiliarity and perceived risks pose similar barriers. It provides a universal framework for navigating consumer resistance in sustainability-driven markets. For managers, the model provides a diagnostic tool for developing stage-specific marketing and intervention strategies to guide consumers more effectively from curiosity to habitual use.</p>