General Mieczyslaw Bieniek took the command from another Polish general, Andrzej Tyszkiewicz in a packed amphitheater said to have been built on the site of a theater erected by legendary conqueror Alexander the Great.
"We have to strengthen stability and security to support the administration, to help rebuild the infrastructure and restore law and order," Bieniek told the audience including representatives of various coalition members in south-central Iraq.
The Polish-led division comprises 9,200 soldiers from 23 countries, providing support to main coalition leaders the United States and Britain.
A Ukranian brass band entertained the attending soldiers from the division which patrol the relatively stable provinces of Najaf, Babel, Karbala, Wasit and Qadisiyah.
Tyszkiewicz, who described his command as the "single greatest challenge of my career", paid tribute to those who died during his watch.
"We mourn our honoured dead and pray that their sacrifice was not in vain," he said.
The most recent bloodshed came in Karbala on December 27 when four suicide car bombs exploded, killing 19 people, including five Bulgarian soldiers and two Thais. At least 200 people were wounded, 64 of them Bulgarians.
Two Polish soldiers have been killed -- one accidentally and one in combat -- since the US-led war began last March.
The top US commander in Iraq, Lieutenant General Ricardo Sanchez, also attended the ceremony and praised the soldiers for having "restored stability" and "given hope" to Iraqis, but warned of tough times ahead.
"This is probably the most critical period we have encountered since the start of our mission," he said.
Bieniek, who arrived with the first batch of 2,500 Polish troops, including 332 crack paratroopers, to replace soldiers at the end of their six-month rotation, has pledged to "deal ruthlessly" with those behind attacks.
Troops who gathered to greet their new general, a 52-year-old veteran paratrooper, said they believed he would continue his predecessor's work but bring a new drive to the multinational division's operation.
"There have been problems in this area, but it is much more peaceful now and hopefully this will continue under the new command," said Polish Sergeant Rafal Kakel.
Lieutenant Colonel Janusz Sobolewski, completing his tour of duty in Iraq, said despite the losses endured by his comrades in arms, he was confident progress was being made.
"We feel we have helped the people here improve the situation. We lost some soldiers, but we hope their lives helped save more lives for the people of Iraq."