In response to the global trend of making sustainable development an urgent task, luxury fashion brands actively embrace it in their corporate philosophies and management policies. However, despite the widespread consensus in the related industry and the strong will of companies for the sustainable development of luxury brands, there are still few cases of luxury fashion brands successfully implementing sustainable development. This study examined the impact of the types of message framing on the sustainability marketing of luxury fashion brands, focusing on their effects on perceived message effectiveness, sustainable brand image, and brand attitudes. An online survey was administered to 464 Korean consumers in their 20s to 40s to test the hypotheses. The results showed that perceived effectiveness was higher for negatively framed messages (loss) than for their positive counterparts (gain). The types of message framing did not significantly affect sustainable brand messages, and no significant difference in perceived brand image was found, regardless of message type. Perceived message effectiveness exerted a significant positive effect on sustainable brand image, and such an image had a significant positive effect on brand attitudes. The results provide implications for related research and practical implications for the development of competitive sustainability marketing strategies for luxury fashion—an industry still in its infancy.