Bush began her trip in the central province of Bamiyan, home to the ancient statues of Buddha that the Taliban destroyed months before they were removed from government in 2001.
In Bamiyan she was also met by Nato-led troops from New Zealand who performed the traditional Maori haka dance for her.
Appeal for aid
Before returning to Kabul Bush met provincial authorities and visited a US-funded police training centre and a planned orphanage.
Bush appealed to the international community not to abandon Afghanistan in the face of resistance from the Taliban.
"We don't need to be intimidated by them," she said, referring to the Taliban,
"The international community can't drop Afghanistan now at this very crucial time."
Karzai, speaking alongside her at a joint news conference at the presidential palace, said he will give donors a "wish-list" in Paris.
"We will come back with some significant assistance," he said.
The US military spends about $100 million a day fighting the Taliban in Afghanistan.
Daily spending on aid by all donors amounts to about $7 million aid experts say.
BBC reporter killed
The billions of aid dollars that have poured into Afghanistan so far, have not translated into improvements in security.
An Afghan reporter for the BBC was found dead in the country's south on Sunday.
The reporter was working in the volatile southern province of Helmand when he was kidnapped on Saturday.
His body was found near the provincial capital Lashkar Gah, the Afghan Independent Journalists Association said.
Speaking on condition of anonymity, an employee with the BBC in Kabul confirmed the death of the reporter who worked for the corporation’s Dari and Pashtu services.
British soldiers killed
In other violence on Sunday, three British soldiers were killed in a suicide attack claimed by the Taliban during a routine foot patrol in the province of Helmand.
The latest deaths bring to 100 the total number of British troops killed in Aghanistan since the 2003 invasion.
Also in Helmand, two Taliban fighters were killed when a mine they were planting in a road exploded prematurely, Mohammad Hussein Andiwal, the provincial police chief, said.
In the central province of Ghazni, six Afghan policemen were killed after Taliban fighters ambushed their convoy.
Two civilians died in the crossfire, the interior ministry said.
In the eastern province of Khost, a district deputy governor and three of his bodyguards were killed in an ambush.
In a separate incident, one man was wounded in Khost's provincial capital when a bomb exploded under a bridge near a regional UN office.
In the southern province of Uruzgan, Taliban fighters ambushed a police patrol in the early morning hours, killing one policeman and wounding two others.