The PMU members were released on Monday and all charges against them were dropped, Kata'ib Hezbollah's military spokesman Jaafar al-Husseini told AFP.
"The judge ordered their release due to a lack of evidence. The arrests shouldn't have happened," the spokesman said.
He said they had appeared at a Hashd military tribunal, as Iraq's various security forces each have their own court system.
Kata'ib Hezbollah is a military unit operating under the PMU - an Iraqi umbrella group which includes more than 40 militia groups fighting Takfiri terrorism.
Iraqi counter-terrorism forces detained the Kata'ib Hezbollah members late Thursday for allegedly planning a rocket attack on Baghdad's Green Zone, where the US and other embassies as well as state buildings are located.
Despite Washington’s accusations, Kata'ib has never claimed responsibility for the attacks.
The Thursday raid on Kata’ib headquarters raised serious questions about Iraq's direction under the new government, as Iraqi leaders describe it as an attempt dictated by the US occupiers.