In the Shiite stronghold of Sadr City in the capital, thousands of supproters of cleric Moqtada al-Sadr decry corruption and poor public services while also rallying against the US military presence and held up pictures of their leader alongside Iraqi flags.
Demonstrations also took place in several central and southern cities.
"We demand the provision of services and electricity, we will demonstrate forever, we will demonstrate until death," said Attiya Jumaa, a 65-year-old protester dressed in traditional robes in Sadr City.
"We demand the government provide services and fulfill all our demands immediatel, immediately!"
Several thousand protesters in the north Baghdad neighborhood gathered on carpets following Friday prayers and shouted: "We want! We want! We want! Quickly! Quickly! Quickly!"
Some hoisted Iraqi flags, but several held up broken fans, fridge doors, lamps and electric heaters to illustrate the lack of electricity, a common refrain among Iraqis who decry a lack of improvement to public services more than eight years after the ouster of dictator Saddam Hussein.
Protesters also slapped their palms against two coffins bearing slogans that called for the country's oil revenues to be better allocated, and for a ration card program, which distributes food to all Iraqis, to be better implemented.
Similar protests took place in the southern cities of Basra, Nasiriyah, Kut and Kufa, as well as in towns in the central province of Diyala.
In the southern port city of Basra, more than 2,000 protesters demonstrated after Friday prayers, some carrying empty jute bags for rice and oil lanterns, again highlighting frustration over ration cards and electricity.
And in Kut, around 3,000 Sadr supporters rallied in the city centre and marched to the provincial council headquarters.
In Kufa, twin city to the holy Shiite city of Najaf where Sadr's office is headquartered, thousands of the cleric's supporters, including religious leaders and members of Iraq's parliament, took to the streets.