The study is a sociolinguistic approach to solving security challenges and enhancing sustainable national development in Nigeria. It argues that language and society influences each other and as such language could be used to solve societal problems. In doing so, the paper x-rays the functions of language in human society as propounded by Halliday and Stubbs. It discusses the multilingual nature of Nigeria, the concept of national development as well as security challenges facing the country. The paper notes that the dominant use English language against the indigenous languages in nearly all communicative domains in Nigeria has failed the nation in its bid to overcome numerous security threats. This may not be unconnected with the low literacy level in the country. As a result, the paper recommends a tripartite language policy vis-à-vis the use of English language, the indigenous languages as well as the Nigerian Pidgin depending on the contextual demand. The paper also advocates the adoption of more indigenous languages, apart from the three major ones- Hausa, Igbo and Yoruba, for use. This will imply a revision of Nigeria's language policy and the constitutional provisions on language.