This study aimed to develop a scale for measuring the online convention service quality (OCSQ) for the effective management of conventions held online. This study followed three steps to develop the measurement scale of OCSQ. First, a literature review of existing research relating to convention service quality was conducted to generate initial OCSQ items. Next, the Delphi method was used to assess the suitability of items for the scale (from 7 May to 10 June 2021). Finally, a survey of attendees of online conventions was conducted (from 26 July to 6 August 2021) to prove the reliability and validity of the items. As a result, in this study, the dimension of security, initially in the category platform service, is separated from it. The results show that online convention service quality has five main components (human services, program services, platform services, security, and interaction services). In the conclusion, we propose the final measurement scale of online convention service quality, with five dimensions and 25 categories. This study has its own value for the initial exploration of online convention service quality, which has emerged as a significant area of convention research. It contributes to academic research and the management of online convention by addressing unique aspects.