The newly elected MPs from the Bangladesh Jamaat-e-Islami-led 11-party alliance, along with independent MPs, were sworn in as members of parliament.
They also took the oath as members of the Constitution Reform Commission.
The oath was administered by AMM Nasir Uddin, the chief election commissioner.
Earlier, Bangladesh Jamaat-e-Islami Nayeb-e-Ameer Abdullah Muhammad Taher said they will not take the oath if the Bangladesh Nationalist Party (BNP) MPs refuse to do so as members of the Constitution Reform Commission.
Taher said the party believes a parliament without constitutional reform is meaningless.