A key feature of the long-observed ‘core’ hegemony in International Relations (IR) is a linguistic one, yet it remains the least explored and confronted, with even today’s ‘Global IR’ discussion unquestioningly taking place in English. However, the non-English IR world is demographically and intellectually immense, and global IR cannot afford to ignore it. This study argues that English dominance in IR knowledge production and dissemination is a pillar of a dependent relationship between an English-speaking core and a non-English periphery. It further argues that this linguistic unilateralism, through assimilation, is structurally homogenising, and impedes the periphery’s original contribution potential in an imperialistic manner. This study examines 135 journals from 39 countries in the linguistic periphery to assess the degree and nature of English dominance in them. It explores the relationship between publication language and ranking and analyses citations to understand whether language matters for being cited in the core. We conclude with recommendations for institutions, individuals, and knowledge outlets, including a call for greater multilingualism, which – though a possible risk for parochialism and provincialism – is necessary for periphery concept development and incorporation into a broadened ‘core’, and a necessary stage to curbing the imperialistic impact of linguistic unilateralism and encouraging a genuine globalisation of IR.