Under the deal, the power plants, each with a capacity of 750 megawatts, will be built in the provinces of Dhi Qar and Muthannah at a total cost of $1.05 billion, a statement from Haider al-Abadi's office said.
GE announced the deal earlier this month, saying it had secured more than $1.4 billion in orders to set up the two plants and provide upgrades and maintenance at others.
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Iraq has struggled for years with major shortfalls in power production and electricity distribution problems.
This leaves many Iraqis with just a few hours of government-provided power per day, giving them the choice of supplementing it with generators or going without electricity in a country where temperatures can top 50 degrees Celsius (120 Fahrenheit) in summer.
Abysmal services, widespread corruption and government posts being distributed along political and sectarian lines were the main factors that sparked anti-government protests starting in the summer of 2015.
The demonstrations, which have continued on and off for more than a year, led to many promises of change by Baghdad, but little in the way of concrete results.