© The Author(s) 2019. In this commentary, we propose using laws in implementing the Healthy Prisons Agenda. We evaluate the efficacy of laws in tackling health inequalities in prisons, provide recommendations on how states can uphold their international commitments that safeguard prisoners’ right to healthcare, and frame prisons as health-promoting settings. We also assess the challenges that can thwart this proposal, such as the non-binding nature of international obligations, global prison overcrowding and the dependency on prison governors and staff for implementation of the Agenda. The commentary concludes by recommending further evaluation of our proposal and testing its potential generalisability to other health-promotion agendas.