The session wasn't without its gaffes, however. After his inaugural speech, interim President Jalal Talabani, a Kurdish leader, walked off the stage, returning after most television feeds of the event were cut off to say he had forgotten to name the new prime minister.
Some Shia legislators were angered by the action.
"We hope that they forgot," Abbas Hasan Musa al-Bayati, a top member of the Shia-dominated United Iraqi Alliance, said.
"This happened because of bad management."
Al-Jafari didn't seem upset, however, telling reporters after the session: "This day represents a democratic process and a step forward."
Some have expressed concern about al-Jafari's close ties to Iran and his work for Iraq's first Shia Islamic political party - the Islamic Dawa Party.
But legislators didn't express any of those reservations on Thursday.
Al-Jafari was named to the government's top post by the presidential council, made up of the president and his two deputies - all of whom were chosen the day before.
Jalal Talabani has been chosen
as Iraq's interim president
Al-Jafari's rise to the top post consolidates the power shift in Iraq, where both the Shia Arab majority and the Kurdish minority enjoy new influence after decades of Sunni Arab political domination.
Shia have a majority of seats in the National Assembly, while Kurds have the second largest bloc.
Sunni Arabs have disproportionately few seats, largely because many boycotted the 30 January elections or stayed home for fear of attacks at the polls.
Al-Jafari spent more than two decades in exile, mostly in Iran, helping to lead anti-Saddam opposition forces in the Islamic Dawa Party, Iraq's first Shia Islamic political party.
The new interim PM also has close ties to Grand Ayat Allah Ali al-Sistani, Iraq's most influential Shia cleric. Al-Jafari's wife is a distant relative of al-Sistani's.
In related news, a lawmaker in outgoing interim PM Iyad Allawi's coalition in parliament said on Thursday that he survived an assassination attempt south of Baghdad after the assembly meeting the previous day.
Shaikh Maad Jasim Mizhir al-Samarmad, also head of the Zubid tribes in Iraq, said he was attacked in al-Wihda district, 35km south of the capital.
The new interim prime minister
takes over from Iyad Allawi (C)
Also on Thursday, a Shia shrine was destroyed by assailants who planted explosives in the structure in the Latifiya area, 60km south of Baghdad, according to Babil police spokesman Muthana Khalid.
The al-Khudir shrine was destroyed by armed men who arrived in several vehicles, Khalid said.
On Wednesday, Kurdish leader Jalal Talabani was chosen for the largely ceremonial job of president, while Adil Abd al-Mahdi, a Shia, and current interim President Ghazi al-Yawir, a Sunni Arab, were elected vice-presidents.
Legislators tried to reach out to Sunni Arabs by naming two Sunnis, al-Yawir and the speaker of the parliament, Hajim al-Hasani, to top posts in the government.
After he was named to the presidency, Talabani urged Iraqi fighters, who are thought to be mostly Sunni Arabs, to talk with the new government. But prominent Sunni Arab groups distanced themselves from the new government.
"We are not related
to any process in this matter of choosing candidates"
Association of Muslim Scholars
"We are not related to any process in this matter of choosing candidates," Muthana al-Dhari, spokesman for the Association of Muslim Scholars, told Aljazeera.
Legislators have been in negotiations over cabinet nominees who will manage government ministries. They have yet to delve into their primary task: drafting a permanent constitution, which is supposed to be finished by 15 August.