Margaret Fuller is chiefly known as the author of the first American feminist manifesto, Woman in the Nineteenth Century, published in 1845. This article undertakes to read Fuller’s work through a republican lens by viewing her discussion on women’s rights as a part of the antebellum debate on American democracy. It also aims to put together two approaches, republicanism and feminism, whose relationship some scholars consider to be antithetical, i.e. Phillips (2000), Friedman (2008) and Hirschmann (2003) but which, in general, has been scarcely analysed. Although republicanism called for freedom and equality among men, it never seriously considered, especially in ancient and early-modern times, the status of women and the recognition of their civil and political rights. However, recent studies, such as Vega (2002), Coffee (2012), Costa (2013) and Halldenius (2015), have tried to reinterpret the possible dialectical connections between women and republicanism, opening up new lines of research on this topic. The purpose of this paper is therefore to provide new food for thought to this contemporary academic debate by adopting a historical approach. This paper argues that Fuller’s use of the concept of ‘liberty’ in her defence of women’s civil and political rights corresponds to Philip Pettit’s (1997) definition of liberty as ‘nondomination’. Taking freedom to mean independence from arbitrary power, Fuller demonstrated that due to their submission to the arbitrary power of men, women totally lacked any measure of independence, and could thus be defined as ‘slaves’. In addition, Fuller bolstered these affirmations by considering a further form of interference resulting from what Alan Coffee (2012) has called ‘social domination’, which was based on cultural values and traditions that condoned women’s exclusion from social, political and working life on the basis of their supposed physical and intellectual inferiority. This did not allow them to exercise their right to freedom as independent agents. The paper demonstrates that thanks to the use of republican paradigms to develop her feminist critique, Margaret Fuller took republicanism a step further and developed a more inclusive and egalitarian model of republican liberty that embraced women. Indeed, her feminist internal critique of republicanism can offer new food for thought to the contemporary academic debate on the compatibility between republicanism and feminism. The research brings to light how Fuller criticized women’s legal status and the institution of marriage, how she compared the condition of women to that of slaves, and how she supported higher levels of education for women as a right and an emancipatory instrument in a free republic.