Traore, who was speaker of parliament, took the oath of office at a ceremony in the capital Bamako attended by leading political figures and among others, the coup leader Captain Amadou Sanogo.
Traore’s most urgent task is to tackle an insurgency by Islamists and Tuareg rebels who have seized the north of the country since the coup, dividing one of the world’s poorest countries into two and creating a major humanitarian crisis.
“I swear before God and the people of Mali to preserve the republican regime… to respect and ensure respect for the constitution… and Mali’s territorial integrity,” he said.
Traore is due to meet with the country’s key military and civilian officials this weekend to hammer out the details of the transitional period.
Under a deal agreed by the coup leaders and West African bloc ECOWAS, Traore has been tasked with organising elections to complete a return to democratic rule.