This article analyses violent and nonviolent male life trajectories in contexts of chronic urban violence, exploring how masculinities and gendered socialisation influence the perpetration of violence in cities of the global South. It draws on the International Men and Gender Equality Survey (IMAGES) Urban Violence Study conducted in Rio de Janeiro (2013–2016), which consisted of 1,151 household surveys in neighbourhoods with high and low homicide rates, fourteen key informant and forty-five in-depth life history interviews with former drug traffickers, members of the police force and local activists. The qualitative and quantitative data suggest that violence transfers from public to private spheres and from one generation to another. Exposure to urban violence as well as childhood experiences of domestic violence contribute to the use of violence. Moreover, chronic fear and experience of violence shape the construction of hyper-masculine and predominantly violent masculinities. Nonviolent male life trajectories are shown to be promoted by fatherhood, active caregiving for biological and non-biological children and additional experiences, such as membership of social groups, that have the potential to widen life perspectives and eventually engender nonviolent and caring versions of manhood. The paper makes the case for a gendered understanding of urban violence, pointing at ways in which nonviolent masculinities evolve and could be promoted.