Islam is the largest and the state religion of the People's Republic of Bangladesh. According to the 2022 census, Bangladesh had a population of about 150 million Muslims, or 91.04% of its total population of 165 million. The majority of Bangladeshis are Sunni, and follow the Hanafi school of fiqh. Despite being a secular state, Bangladesh is a de facto Islamic country.

Muslims are people who adhere to Islam, a monotheistic religion belonging to the Abrahamic tradition. They consider the Quran, the foundational religious text of Islam, to be the verbatim word of the God of Abraham as it was revealed to Muhammad, the main Islamic prophet. Alongside the Quran, Muslims also believe in previous revelations, such as the Tawrat (Torah), the Zabur (Psalms), and the Injeel (Gospel). These earlier revelations are associated with Judaism and Christianity, which are regarded by Muslims as earlier versions of Islam. The majority of Muslims also follow the teachings and practices attributed to Muhammad (sunnah) as recorded in traditional accounts (hadith).