In this article, I explore the relationship between witness-bearing arts as a form of creative activism designed to respond to social injustices. In the first section, I present some common features of bearing witness, as conceptualized within media studies and journalism. Then I explain how artworks placed in the streets can bear witness in a similar way. I argue that witness-bearing art transmits knowledge about certain unjust and harmful events, which then places a moral burden or responsibility on the viewer. (...) To defend this view, I offer some examples of activist art that bears witness to certain events. I suggest that witness-bearing art is placed in the streets in order to make certain truths publicly available, by offering evidence of them embedded in the artwork. The final section considers why the bearing witness is especially effective for activist art. Witness-bearing art plays a crucial knowledge-transmitting function, one which enables art to engage in creative activism. I conclude by considering how witness-bearing art offers a powerful and persuasive voice for the oppressed. (shrink)