Six ministers and two state ministers took oath to join an election-time Cabinet.
President Abdul Hamid administered the oath at the presidential palace.
The BNP and its 18-party alliance have repeatedly rejected Hasina's call to join the all-party government, saying elections would not be credible under her leadership.
The BNP termed the all-party cabinet as "farce".
BNP's acting secretary general Mirza Fakhrul Islam Alamgir earlier said: "It's just another farce of the grand alliance government" while the party's joint secretary general said "the all-party government is just another version of the grand alliance government".
All the new ministers are from the constituents of the Awami League-led grand alliance.
The new ministers are: Amir Hossain Amu and Tofail Ahmed (Awami League), Rashed Khan Menon (Workers Party), and Anisul Islam Mahmud, Ruhul Amin Hawlader and Rawshan Ershad (Jatiya Party). The state ministers are: Mujibul Haque Chunnu and Salma Islam (Jatiya Party).
The opposition has long been demanding restoration of a non-party caretaker government, a constitutional provision which was annulled in June 2011.
The formation of an all-party government headed by Hasina has pitted the ruling Awami League against the BNP, raising fear of violence ahead of the polls to be held by January 25.
Hasina called on the President last evening and explained her idea about the all-party government. Her meeting came hours after the former Cabinet held an emergency meeting.
Last week, the ministers handed over their resignation letters to Hasina to pave the way for the formation of the all-party government.
The development came as violence over the deadlock killed 30 people while at least 76 people, including children, were burnt and over 500 vehicles were torched as the BNP and its major ally, fundamentalist Jamaat-e-Islami, staged street protests and enforced 10-day shutdown in the past 21 days.
The BNP and Awami League could not start a much talked about proposed dialogue despite what they claimed their "readiness" for the talks to overcome the impasse, which has become a concern for the international community.
A visiting senior US official today said Washington was firmly optimistic about the proposed dialogue to end the political deadlock as she wrapped up a three-day tour after talks with two top Bangladesh leaders.
"I'm optimistic we will see the dialogue to take place...I have reasons to have that hope," US assistant secretary of state Nisha Desai Biswal told reporters.
She said Washington was "pushing for the dialogue" between the ruling Awami League and BNP, adding that the talks should take place immediately.
"This (formation of the all-party government) indicates the urgency of the dialogue," she said when asked if the development ignoring BNP's opposition could impede the proposed "constructive dialogue".
Biswal also sharply criticised the continued violence as the opposition was spearheading a street campaign over the electoral system saying: "Violence of any kind is not accepted in any democratic process."
Replying to a question about the reported differences between the US and India on the political deadlock in Bangladesh, Biswal said she had no idea of any such gap.
She, however, acknowledged recent comments by Indian High Commissioner in Dhaka Pankaj Saran that India was in consultation with the US over the issue.
Meanwhile, a major ally of the ruling Awami League, Jatiya party, has announced its disassociation with the ruling coalition to float a new right-wing alliance.
Former president H M Ershad of Jatiya party met Allama Ahmed Shafi, the chief of a newly-found extreme right-wing group Hefazat-e-Islam, a forum of teachers and students of unregistered madrasa.
The government last week amended an election law allowing people, who have joined or changed their political party overnight, to contest polls. Previous law disqualified political turncoats from national elections.
Bangladesh sends 152 soldiers to gallows for 2009 mutiny
IN PHOTOS: Capitol Hill celebrates its first-ever Diwali
Bangladesh deadlock: Zia floats proposal for interim govt
Death toll in Bangladesh violence rises to 6
Bangladesh: BNP leader sentenced to life imprisonment