Toure was accused by the current government of President Ibrahim Boubacar Keita of treason
Toure, known by the acronym ATT, came to power in 2002, and fled to Senegal after being overthrown by a military junta in 2012 just as he was preparing to end his final term in office.
"The elected representatives of the people have voted by secret ballot on the fate of former president ATT, and have decided not to pursue him after leading Mali for 10 years," an opposition lawmaker told AFP after Friday's vote.
Under Malian law, it is lawmakers who sit in judgement on current or former presidents.
Toure was accused by the current government of President Ibrahim Boubacar Keita of treason related to the failure of soldiers to tackle an Islamist insurgency in the north of Mali.
The coup led by army captain Amadou Sanogo toppled what had been heralded as one of the region's most stable democracies and precipitated the fall of northern Mali to Al-Qaeda-linked groups until a French-led military operation in 2013 forced them out of the towns.