This paper analyzes how activists used a parliamentary petition to overcome legal and political barriers and mobilize openly for gay rights for the first time in Singapore. Unlike societies where rights mobilization has political legitimacy, exercising and claiming rights in the de facto one-party state are non-conformist behaviours and face greater limitations. Gay rights activists in Singapore not only struggle with the state and their opponents over the right to equality; compared to their counterparts in liberal democracies, they also have to overcome stronger restrictions on political access and civil-political liberties that enable or protect rights mobilization. This paper therefore describes and analyzes a politics of rights under authoritarian conditions and the complicated consequences of legal resistance and rights mobilization. Although the petition campaign transformed collective grievances, expanded activists’ support base, and opened up new tactical possibilities, it also provoked intense, third-party opposition and foreclosed other avenues of mobilization.