Prior social media research has overlooked the impact of social capital on social media attachment and brand equity. This study analyzes the relative influences of bridging and bonding social capital attachment on social media attachment and whether social media attachment is transferred to brand attitudes. Additionally, this research examines whether the offline psychological distance of consumers plays a moderating role between social capital and social media attachment. This research conducts a survey. 220 questionnaires are collected and 203 questionnaires are used for testing hypotheses. Hypotheses test results show that bridging social capital and bonding social capital have a significant impact on social media attachment. This study also analyzes the moderating role of offline psychological distance between social capital and social media attachment. The influence of bridging social capital on social media attachment does not increase when offline psychological distance becomes close; thus, the synergy effect hypothesis is not significant. However, the offset effect is significant. Since social media attachment increases positive brand attitudes, social media attachment accumulated by social capital is transferred to brand attitudes.