The establishment of marine protected areas is a cornerstone of global marine biodiversity conservation efforts. A critical factor in whether these marine protected areas deliver conservation benefits is the level of compliance with regulations. We first present a psycho-social model of determinants of compliance behaviours amongst recreational fishers across Australia. The model is then used to inform a social marketing campaign aimed at promoting self-compliance (i.e., intrinsically motivated rather than through fines) amongst recreational fishers in the Great Barrier Reef Marine Park. We show that across three diverging Australian contexts, recreational fishers are motivated by the same social-psychological determinants, raising the possibility for a national-scale approach to promoting compliance behaviours. Using A-B testing, our social marketing campaign demonstrates significant room for improvement in social-marketing efforts to date and shows that recreational fishers are most responsive to messages and imagery with broad appeal. The research advances the use of, “soft-touch” strategies as compliments to enforcement for achieving compliance with marine protected areas in Australia.