The national language and official language of Bangladesh is Bangla according to the third article of the Constitution of Bangladesh. Almost 99% of Bangladeshis speak Bengali as their first language. Bengali Language Implementation Act, 1987 made it mandatory to use Bengali in all government affairs except in the cases of foreign relations. According to a 2022 census, Bengali is predominantly spoken by 99% of the country's population and it also serves as the national language of the nation. The indigenous people of northern and southeastern Bangladesh speak a variety of native languages. According to the Ethnologue, there are 36 indigenous living languages, which include 17 Tibeto-Burman, 10 Indo-Aryan, 7 Austroasiatic and 2 Dravidian languages in Bangladesh. Bangladesh has 44 indigenous languages according to Professor Shameem Reza.

The Indo-Aryan languages are a branch of the Indo-Iranian languages in the Indo-European language family. As of the early 21st century, they have more than 800 million speakers, primarily concentrated in Bangladesh, India, Pakistan, Sri Lanka, Maldives and Nepal. Moreover, apart from the Indian subcontinent, large immigrant and expatriate Indo-Aryan–speaking communities live in Northwestern Europe, Western Asia, North America, the Caribbean, Southeast Africa, Polynesia and Australia, along with several million speakers of Romani languages primarily concentrated in Southeastern Europe. There are over 200 known Indo-Aryan languages.