Achieving sustainability goals in the food system should be informed by consumer demand that signals the market trend and drives systemic changes. This study examines the efficiency of sustainability cues in influencing consumer choices of seafood among consumers in Southern China. The preference and willingness to pay for each seafood attribute are estimated using the Latent Class Logit model. The results show that respondents strongly believed in governmental certifications and were more willing to pay for domestic seafood certified to public standards over imported seafood with third-party sustainability certifications. By integrating individual characteristics into the membership function, this study finds that the preference for sustainability cues and other authenticity cues is related to seafood consumption habits and education. The study highlights the efficiency heterogeneity of sustainability cues, providing valuable insights for formulating public policy and developing marketing strategies that promote sustainable consumption.