The United Nations’ ‘System-wide Action Plan on Gender Equality and the Empowerment of Women’ (UN-SWAP) is a framework to hold entities in the UN system accountable for advancing the UN's gender-equality goals. Including 18 indicators and requiring annual reporting on progress, it integrates gender mainstreaming into the UN's system of results-based management. In this article, we ask: how does the UN-SWAP produce change in the UN system, and to what extent can this change be considered gender-transformative? We approach the instrument as a distinctively feminist accountability mechanism in a policy ecosystem traversed by diverse power dynamics. Based on reviews of UN-SWAP documents, interviews with gender experts involved in its implementation, and participant observation, we argue that the UN-SWAP has generated both a taming of gender-equality goals and elements of transformative change in terms of outcomes and processes. It has accelerated the incorporation of gender considerations into key administrative processes of UN entities but has been less successful with regard to achieving the necessary allocation of resources and equitable staffing. While we confirm a tendency towards a narrowing of feminist goals—as expected from the literature on indicators—the mechanism has also empowered a network of Gender Focal Points and advisers. By offering a feminist way of doing accountability, based on trust and learning rather than sanctions and shaming, the UN-SWAP thus generates power that comes from acting in concert and contributes to transforming administrative processes and cultures.