This thesis research was carried out due to the development of information and communication technology which has an impact on trading activities. The impact of these developments is currently the existence of trade conducted online, which results in the emergence of the use of digital contracts as a form of agreement which often causes disputes and in business prefers online dispute resolution, especially online arbitration. However, in Indonesia the legal basis for online arbitration has not specifically regulated online arbitration awards. This research was conducted with the aim of knowing and studying the legality of online arbitral awards in Indonesia based on the theory of legal certainty and also the relevance of Law Number 30 of 1999 about Arbitration and Alternative Dispute Resolution to online arbitration, especially regarding online arbitration awards in Indonesia. This research is a normative research with a conceptual approach and statutory approach. The data source is in the form of secondary data consisting of primary legal materials and secondary legal materials, which are analyzed using legal analysis methods. Drawing conclusions using a deductive thinking process. The theory of legal certainty is used as an analytical knife in reviewing research results. The results of the study show that online arbitral awards when associated with Gustav Radbruch's theory of legal certainty still occur in a dilemmatic choice and Law Number 30 of 1999 concerning Arbitration and Alternative Dispute Resolution has not yet accommodated arrangements regarding online arbitration in Indonesia, especially regarding online arbitration awards, this causes Even though the decision has legality, if there is no law that regulates it for certain, then the aspect of legal certainty does not necessarily exist.