Seafood consumption has an impact on both consumers’ health and on the marine environment, making the integration of health and sustainability aspects in information and recommendation messages for consumers highly topical. This study presents the results of a consumer study in terms of the impact of exposure to a message about health and sustainability aspects of seafood on 986 participants from Belgium and Portugal. Possible drivers for behavioural change regarding seafood consumption frequency and sustainable seafood buying frequency are studied following exposure to the message. Initial behaviour emerges as the most important factor triggering a change in the intention to consume seafood twice per week and a change in the intention to buy sustainable seafood. A higher health benefit perception resulted in an increased intention to consume seafood twice per week. Attitude towards the message and the option to optimise consumers’ choice of seafood species favouring sustainability were significant determinants of change in the intention to buy sustainable seafood. Different stakeholders may take the results of this communication strategy into account and, consequently, contribute to a seafood supply and related communication that supports public health and the marine environment.