Although heterotopia has been widely studied as relating to the marginal or subliminal sites of the city, the ubiquity of social media and mobile technology has facilitated the development of transient forms of heterotopia in support of large-scale urban movements. Using the case of Hong Kong’s networked mall protests, this article examines acts of mobile activism, whereby the urban landscape and its routines are temporarily reconfigured and turned into spaces of popular dissent joined by people in all walks of life. Drawing on multiple data sources and guided by connective ethnography, this study illustrates how digitally connected protestors created fleeting counter-sites in and across shopping centres to defy urban policing and subvert the spatio-temporal order it imposed. Rather than reclaiming urban public spaces to offer reservoirs of freedom, the protestors enacted occasions of opposing otherness not outside of urban repression but rather carved out of it as a nimble, counter-normative type of political resistance. By charting the contours of several types of these networked mall protests, this article reveals how contemporary mobile activism invents and reproduces alternate protest time-spaces. Focusing on their capacity to refashion contentious political life in the city, it offers nuanced insights into the latest form of spatial political engagement in a networked urban setting.