Development always produces positive and negative impacts. The positive impact is advancing civilization and the negative impact is detrimental to life. The negative effect of the action is the development of crime from conventional to modern, one of which was born due to the use of the internet. One of the traditional problems that are now increasingly modern is online prostitution, known as cybercrime. With this research problem, the aim is to determine the legal rules of online prostitution in Indonesia and the urgency of its criminalization. Using the normative method, it was found that online prostitution poses a problem that only pimps will get criminal penalties. This provision is certainly unfair because the giver, perpetrator, and user must also be subject to criminal sanctions. In its laws and regulations, Indonesian law still does not regulate online prostitution activities, even conventional prostitution. However, in the Criminal Code, several article formulations indirectly regulate prostitution activities, namely articles 296 and 506 but only handle pimps. Seeing this legal vacuum and acts of prostitution that do not follow the values in society and advances in information and science, there are three reasons for the urgency of criminalization, namely philosophical, juridical, and sociological. Philosophically, online prostitution is against Pancasila, the first and second precepts, and the 1945 Constitution of the Republic of Indonesia. Due to juridical reasons, there is a legal vacuum and legal uncertainty. The sociological sense that online prostitution does not follow the norms in society causes unrest and can cause various dangerous diseases. Keywords: urgency, criminalization, prostitution, online