This article is a critical interdisciplinary study of biohacking as a specific case of transhumanism and its goals of enhancement and age intervention. It focuses on the organising principles underlying the biohacking movement's relationship to ageing and technoscience. The argument traces how the historical and scientific body technologies of molecularisation, functional age, optimisation, and quantification made possible the biohacking vision of the ageing body as amenable to modification, enhancement and improvement beyond its natural limits. Conclusions consider the wider implications of biohacking by pointing out four important issues that frame our cultural ambivalence about ageing: the tension between biohacking's supposedly liberating enhancement technologies and their obeisance to a tyranny of self-disciplinary practices and the authority of bio-data; the social meaning of biohacking hierarchies of human value, based on modifiable fitness and enhanceable performance; the implications of the biohacking program for gendered ageism; and the ethical limits of biohacking, not only in terms of potential harms to a person but what it can mean to exceed the natural limits of life.