As patients became the most significant stakeholders for their survival, healthcare organizations strived to satisfy healthcare needs of the public and maintain ongoing relationships with patients. Moreover, the social media has been used to promote patients to become more empowered not only by providing patients with more health information but also by allowing them to develop online patient communities through which they can share various kinds of computer-mediated social supports. While South Korea is considered one of the fastest growing social media users, it is not clear the relationships among computer-mediated social support, patient and doctor-patient communication. During November 2017 to January 2018, a total of 272 Korean thyroid cancer patients responded to surveys regarding the influence of online community activity on doctor-patient communication. A path analysis was used to analyze the relationship between Korean thyroid cancer patients’ online community activity and perceived social support, and the relationship between perceived social support and their behavioral intention to participate in doctor-patient communication. The results show that the more Korean thyroid cancer patients participated in online communities, the greater they showed perceived social supports from online community members. This study also indicates that Korean thyroid cancer patients have actually perceived informational, emotional, and esteem support from online community members. Moreover, patients who participated in online community activity had a strong intention to actively participate in patient-provider interactions. The findings from this study will not only contribute to the theoretical understanding of computer-mediated social support but also provide fundamental knowledge about patient-provider interaction for healthcare specialists.