The blasts went off during morning rush hour in Kut and Aziziyah, both in Wasit province bordering the capital, while vehicles rigged with explosives were also detonated in the southern cities of Nasiriyah and Basra.
At least 14 people were killed and 44 wounded in the attacks, security and medical officials said.
The deadliest attacks struck in Kut and Aziziyah.
In Kut, Wasit’s provincial capital, a car bomb exploded outside a restaurant in an industrial area packed with vehicle repair garages, killing seven people and wounding 15.
Another car bomb in Aziziyah in the town’s main marketplace and near a Shiite mosque killed five and wounded 10.
The violence was the latest in a spike in attacks nationwide, with last month registering the highest death toll since 2008, sparking fears of a return to the all-out sectarian war that blighted Iraq in 2006 and 2007.