Al-Arabiya cameraman Ali Abd al-Aziz died on 18 March from a gunshot wound to the head. Correspondent Ali al-Khatib died from his wounds in hospital the next day. Both were Iraqis.
Colleagues said US troops fired on their car near a checkpoint in central Baghdad. The US military initially said it was unlikely its bullets had killed them.
On Monday, a US military official said an investigation into the deaths showed troops were responsible, but had acted "within the rules of engagement".
US soldiers were aiming at a different car, a white Volvo that had driven through the checkpoint at high speed, the investigation said. Al-Arabiya's grey Kia car was 50m to 150m down the road, trying to turn when it was accidentally hit, the military said.
"The investigation concluded that no soldiers fired intentionally at the Kia," the US military said in a statement.
"Only one soldier saw the Kia leave the scene and was unaware that the Kia had been struck by gunfire or that its occupants had been killed or injured. We regret the accidental shooting of the al-Arabiya employees."
The driver of the Volvo was also killed in the incident.
A senior military official claimed troops fired at the Volvo in self-defence. He said it was driving at high speed, and rammed a US Humvee hard enough to push it back 4m.
He said eight soldiers, worried about car bombs, had fired up to 10 bullets each at that car. Its driver was killed.
Colleagues of the slain journalists
react to news of their deaths
Several bullets accidentally struck the Arabiya car.
"The soldiers were acting within the rules of engagement," he said. "At this point this is seen as an accident. At this point the soldiers were working within the rules of engagement."
He said the investigation was finished.
Before the 18 March incident, at least four journalists had been killed by US forces in Iraq.
Iraq 'most dangerous'
Last week, an Iraqi cameraman working for US network ABC was shot and killed while covering clashes west of Baghdad. Witnesses said he was shot by US troops.
A senior military official said on Monday that the US military was considering whether to investigate the incident.
"The soldiers were acting within the rules of engagement ... At this point this is seen as an accident. At this point the soldiers were working within the rules of engagement"
Senior US military official
The Committee to Protect Journalists (CPJ) has said: "Iraq is the most dangerous place in the world to work as a journalist." In 2003 alone, according to the CPJ's estimates, 13 journalists died in "hostile acts". Others died due to illness or accidents.
Amongst those killed was Aljazeera TV's correspondent, Tariq Ayoub, who died in a US air strike on the satellite channel's Baghdad bureau.