Al-Sadr's comments follow a slew of similar demands from Iraq's political and religious elite after months of stalled progress on a reform package Iraqi Prime Minister Haider al-Abadi proposed last summer.
Among a series of economic and political reforms, Al-Sadr called for Iraq's powerful Shiite militias to be formally incorporated into Iraq's existing security forces.
This would also include Sadr's own militia, Saraya al-Salam, which was formed following the fall of Mosul to the Islamic State group in June 2014.
"Let it be known that the non-implementation of these items is a betrayal of Iraq and its people," al-Sadr said. Iraq is engaged in a humanitarian and security crisis that erupted as the Islamic State group swept across the country.
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It is also battling a crippling economic crisis that threatens to further choke the government's ability to provide basic domestic services.
Earlier this month, Grand Ayatollah Ali al-Sistani, Iraq's top Shiite cleric, also signaled his dissatisfaction with government inaction by suspending his Friday sermons.
"All these issues have been repeated endlessly until our voices became sore," he said in a speech in late January.
Once considered an indispensable powerbroker in Iraq, al-Sadr's political clout has waned recently as other Shiite militia leaders with closer links to Iran have grown in prominence following the collapse of the Iraqi security forces.
As IS pushed has toward Baghdad, Shiite militias have filled the vacuum and have grown more powerful than the country's own security forces.