This article uses the app Health Code, a smartphone-based application for contact tracing and risk assessment that serves as a COVID-19 health passport, as an example to explore how “biometric citizenship,” a new mode of preemptive social regulation, functions and malfunctions in contemporary China. First, through a review of China's transition from socialism to neoliberalism, the authors trace how the tenet of citizenship shifts from biological/biopolitical to biometric as the party-state's agenda changes along the process. Second, drawing on media coverage and comments from social media, we show how Health Code consolidates the biometric paradigm of citizenship and turns the relatively stabilized temporal basis of biological/biopolitical citizenship into fragmented temporalities to tighten social control. This preemptive control system improves the state's acumen for self-revamping and self-preservation and enhances its capacities to harness people's re/productivities. It also disrupts the habituated way of living and further marginalizes the groups with diminishing re/productive potentialities.