Biosecurity politics in New Zealand is implicated in the constitution of a new dimension of citizenship, a biosecure citizenship. This form is distinct in that the political determinants of citizenship do not fully rest on the individual body, but on the body’s connections to other entities, the inter- and intra-active symbiotic condition of human-non-human ‘living together’. Through its constitutive role in enabling the ‘dangerous’ mobility of pathogens, viruses and invasive species, symbiotic individuality has become politicised as a matter for state determination and control. Contemporary articulations of biosecure citizenship emphasise a variety of contractual and non-contractual responsibilities, which augment the national coordinates of citizenship, reconstitute symbiotic individuality, and justify the state penetration of the private sphere. Drawing on biosecurity legislation, public education campaigns and research with community weed removal projects, I chart the reinforcement and practice of this biosecure citizenship. I argue that there is an urgent need to democratise decisionmaking about the construction of biological threat, about where and how to make cuts in our symbiotic associations with different species, and between species and spaces. By articulating biosecure citizenship not only as a discourse of ecological responsibility but of rights, biosecurity could be reinvigorated as ‘bios-security’, the inclusive politics of continually questioning the ecological good life.