This article investigates how Muslim politicians in northern Nigeria have used the institutions of democracy and federalism to extend Shari'ah into the penal codes. The principal task of this paper is fourfold. First, it considers theoretical perspectives on the conceptualization and essence of federalism and democracy in the service of governance. Second, to challenge the overpraised thesis on the role of democracy in implementing Shari'ah, it explores the interplay between federalism and democracy in the struggle of Muslims in northern Nigeria to assert their religious identity. Third, it examines how the extension touches on the essentialism of democracy and federalism. Fourth, in terms of managing the confluence of democracy and federalism, it investigates how and why the 1999 constitution has failed to resolve the paradox of the institutional forces of democracy and federalism in extending Shari'ah to the penal codes. The paper concludes that, to address the emerging dysfunctional aspects of the extension of Shari'ah to the penal codes in the north, including sectarian tensions, interconfessional conflicts, and the menace of Boko Haram, the Nigerian government must do two things: it must work with and support grassroots Islamic civil organizations in the north to emphasize the welfare aspects of Shari'ah, and it must persuade respectable northern Nigerians to rise above partisan politics and mediate between the members of Boko Haram and political authorities.