This study investigated how sustainability-related messages of cotton textile and apparel products influence consumers’ attitudes toward the message and interaction with other consumers in social media. Three hundred and eighty-eight online survey data of US consumers investigated the effects of perceived information and emotion toward sustainability practice messages on attitude toward and social interaction with other consumers and the effects of attitude on social interaction in social media. The results confirm that emotion is an influential variable, and, specific, positive emotion is an influential variable for attitude, and attitude influences social interaction with other consumers of sustainability practice messages. Negative emotions influence both attitude and social interaction. The information does not influence attitude but directly impacts social interaction, which may bring the purchase intention of sustainable fashion products. Thus, apparel marketers should consider emotionally sustainable promotion messages when tailoring their brand communications on social media. This study helps clarify the relationships between emotion and social interaction for sustainable fashion products. It also contributes to the theoretical foundation and has implications for sustainable fashion marketing and management in social media.