Recently, O2O services are showing rapid growth, but continuous online and offline quality improvement and competitiveness are required. The purpose of this study was to verify the effect of online platform and offline brand quality of accommodation O2O on satisfaction, attachment, and relationship continuity and sharing intention. A survey was conducted on accommodation o2o service users, and 353 samples were used for research analysis, excluding inappropriate data. The hypothesis of this research model was verified through structural equation model analysis. The analyzed research results are summarized as follows. First, all sub-variables of online platform quality had a significant effect on online platform satisfaction, and all sub-variables of offline brand quality had a significant effect on offline brand satisfaction. Second, online platform satisfaction had a significant effect on offline brand satisfaction. Third, online platform and offline brand satisfaction had a significant effect on O2O service attachment. Fourth, service attachment had a significant effect on relationship continuity and sharing intention. In the conclusion of this study, marketing implications for improving online and offline quality and maintaining sustainable customer relationships in the accommodation O2O industry were presented.