This article explores the online discourse of the Oduduwa nation secessionist movement in Nigeria, which seeks the independence of the Yoruba ethnic group from the Nigerian state. Using critical stylistics as a framework, the study analyzes how online participants use language to express their resistance and legitimize their cause. The empirical data consists of Oduduwa nation-related posts from Nairaland, a popular Nigerian online forum, collected between September 2020 and September 2021. The study adopts a qualitative approach and identifies the dominant themes and linguistic strategies that characterize the discourse. The discursive engagement of the Oduduwa republic movement is surrounded by discourse issues, such as the amalgamation pact of 1914, the perceived ethnic oppression of the southern region, and the lingering Biafra nation secessionist agenda. The findings reveal that the online participants use various linguistic-stylistic strategies, such as naming and describing, negating, representing actions and events, equating and contrasting, exemplifying and enumerating, to construct their identity, challenge the status quo, legitimise their activities, and mobilize support for their movement. The study also reveals that the discourse is influenced by the historical, political, and social contexts of Nigeria; such as the colonial legacy, the ethnic diversity, and the security challenges. As the burning issue of secession continues to resurface in Nigeria’s political landscape, its intense contestation in online space poses a threat to nationhood because cyberspace can be harnessed to sustain the propagation of separatism and national disintegration. The study contributes to the understanding of online civic engagement and social activism in Nigeria and highlights the role of language in shaping and reflecting social movements.