The swearing-in ceremony was carried live on state-run Pakistan Television, and most of the incoming ministers appeared to be holdovers from the previous Cabinet, dissolved earlier this week.
President Asif Ali Zardari and Prime Minister Yousaf Raza Gilani presided as about 20 officials sat around a table designated for the new Cabinet - though it was not clear if that will be the final number of ministers. Authorities have suggested that in the next few days, more ministers could be sworn in.
The key ministries - finance, interior and law - retained the same heads. Notably absent was the former foreign minister, Shah Mahmood Qureshi. A government statement late Friday designated only a deputy minister, Hina Rabbani Khar, for the Foreign Ministry for now.
The previous Cabinet had more than 50 ministers, as well as additional members who held titles such as advisers or deputy ministers. Opposition leaders have demanded that a smaller Cabinet take over.
The ruling party has sought to appease the opposition in recent weeks in a bid to gain broader support for financial reforms demanded by international lenders whose billions are keeping Pakistan's economy afloat. Analysts say shrinking the Cabinet is a good start but may not be enough to get the opposition to agree to reforms such as a new sales tax.
The ruling Pakistan People's Party, however, has insisted that the Cabinet change is driven primarily by the need for fiscal austerity, not what the opposition wants. It has not said how much money it would save by reducing the body's size.
Qamar Zaman Kaira, who lost his post as information minister and is at present only a lawmaker, said the party was responsive to demands from all sectors, including the people themselves.
"I believe that the nation shall thank us," he said.
Pakistan's economy relies heavily on loans from the International Monetary Fund and the government has struggled to raise revenues, in part because many residents avoid paying taxes.
Chronic power shortages have hampered economic growth and floods last year caused massive damage to infrastructure and other sectors.