In recurring emergencies, frontline health care professionals (HCPs) have taken on a dual responsibility of not only serving as medical professionals for patients but also disseminating medical knowledge online for the public to alleviate their anxiety. They are expected to perform both online and offline organizational citizenship behavior (OCB). However, HCPs carry out their duties with high risks, inhibiting their OCB. This study aims to understand how to effectively and efficiently integrate online and offline support to facilitate HCP’s online and offline OCB in recurring emergencies. Data was collected from a survey among HCPs amid the second wave of the COVID-19 pandemic from March to April 2021. It was found that perceived support helps promote HCPs’ OCB through increasing optimism and resilience. Moreover, offline problem-focused support is more helpful than online emotion-focused support for HCPs with more knowledge of the emergency.