Methods, systems, and media for generating an advertisement from a video stream are provided. In accordance with some embodiments, the method comprises: receiving, from a first user device, advertisement parameters associated with an advertisement campaign for placing an advertisement based on the advertisement parameters, wherein the advertisement parameters include one or more keywords; associating the advertisement parameters with an identifier of the first user device; receiving, from the first user device, a live video stream; receiving, from a second user device, a request to present an advertisement; identifying the live video stream based at least in part on the one or more keywords; generating the advertisement using the live video stream and the advertisement parameters; and causing the advertisement to be presented on the second user device as the advertisement.