The integration of Artificial Intelligence (AI) into Nigerian higher education has transformative power on the landscape of teaching and offers potent tools for enhancing instruction delivery and learning outcomes. However, Mathematics lecturers face significant barriers in adopting AI-enhanced instruction. This scoping review identifies the challenges and potential solutions. Four research questions guided the study and through theories of diffusion of innovation (DIT) alongside technological pedagogical content knowledge (TPACK), it reviewed relevant literature from peer-reviewed journals, conference proceedings, and policy reports on AI in higher education and Mathematics instruction in Nigeria. Insights from this study would be of critical importance to educational policymakers, institutional administrators, and lecturers themselves, as it would provide a roadmap for scaling AI-enhanced teaching innovations in Mathematics Departments. The study identified that technical challenges, pedagogical resistance, institutional limitations, and attitudinal barriers could be overcome through the implementation of national education policies establishing institutional AI support centres for lecturers; incorporating AI training in pre-service and in-service teacher education; and facilitating AI-enhanced curriculum development and review. It concluded that AI serves as a valuable resource for guiding educational innovation and helping institutions to improve teaching quality, address barriers, and enhance students' learning outcomes in Mathematics. It recommends among others that higher education institutions should invest heavily on digital infrastructure, frequent training programmes for lecturers, and institution-based policies that encourage the adoption of AI technologies while maintaining the core values of traditional teaching.