This article discusses Henry Jenkin’s concept of transmedia as the art of making worlds, in reference to the building of fictional worlds, to theoretically expand on this definition for the documentary genre. If Bill Nichols stated that non-fiction genre has a great persuasive power -because of the indexical nature of its images and sounds, and the psychological effect of verosimility created in the audience- we defend the idea that this character is increased through the transmedia storytelling. The immersion, extrability and performativity of this kind of narrative form lead to an active user role in the transmedia world, that coincides with his own world, the real one. That is why numerous activist projects have used the transmedia documentary as an opportunity for critical thinking and social change.