"He shall be hanged till death," ruled a three-member panel of judges of International Crimes Tribunal-2 headed by Justice M Enayetur Rahim.
The tribunal said it found former militia commander guilty in two of the five charges brought against him.
64-year-old Hossain, clad in a white dress, was handed death for the killing of 33 civilians at his home district in central Brahmanbaria district on August 22, 1971.
Hossain was sentenced to life imprisonment in another charge of killing while the prosecution brought against him the charges of murder, abduction, confinement, torture and looting homes of their valuables.
Hossain was associated with fundamentalist Jamaat-e- Islami, which was opposed to Bangladesh's independence.
After the defeat of Pakistan, he managed to join Awami League, which led the liberation war.
So far, Hossain is the only Awami League leader to face trial for war crimes.
The party expelled him two years ago when his role in 1971 resurfaced after tribunal initiated the process for the trial of the war criminals.
Ahead of his expulsion, Hossain served as the Awami League organising secretary of a union parishad, the lowest administrative tier at grassroots, for 16 years until 2012.
