The rapid development of artificial intelligence (AI) presents important opportunities for strengthening language security in multilingual societies such as Nigeria. This conceptual paper examines how AI can support the preservation, accessibility, digital representation and sustainable use of indigenous Nigerian languages, while also identifying the technological, infrastructural, ethical, policy and institutional challenges that may constrain implementation. Drawing on the literature presented in the paper, the discussion focuses on natural language processing, speech recognition, machine translation, digital language archives and AI-assisted learning systems as mechanisms for improving linguistic inclusion and reducing digital marginalisation. The paper argues that language security should be treated not only as a cultural concern but also as an educational, communication and national-development issue. It proposes an AI-driven framework built around five interrelated pillars: policy and ethical governance; language documentation and digital resources; technological infrastructure; education and human-capacity development; and stakeholder and community participation. The paper concludes that sustainable AI-based language security in Nigeria requires coordinated institutional action, equitable digital access, culturally responsive technology design and meaningful participation by indigenous language communities.