In the digital media environment, public engagement with science around controversial scientific topics such as genetically modified organisms (GMOs) has greatly expanded. But the public's role as science communicators in such engagement has been virtually ignored. Through an online ethnography of the discussion of GMOs on Zhihu, the biggest Chinese knowledge-sharing network, this study identifies a new group: citizen science communicators involved in online science communication. The emergence and popularity of this new group brings public engagement with science to a new stage – public engagement with science communication – and changes the role of the public in science communication from audiences to communicators. The development of digital platforms and the revolution of the understanding of science communication all contribute to the emergence and popularity of this group in the Chinese digital environment.