Europe's leaders are hoping Monti's pedigree will help in formulating new funding ideas to avoid the deadlock that occurs every seven years when the 28-member bloc debates its common budget.
Aware of the uphill challenge he faces in leading a working group on the subject, Monti joked that one of the reasons he took the job was "a great curiosity about a subject that is practically impossible to resolve."
European Commission President Jose Manuel Barroso said he had great faith in Monti, an economist who gained the nickname "Super Mario" during his time as a European Commissioner.
"I have had the pleasure of working closely with Mario Monti in the past and can think of no better person to steer the work of the group with professionalism, integrity and intellectual rigour," Barroso said.
The commission has already agreed broad outlines for new funding ideas, he said, including a tax on financial transactions, removal of VAT exemptions and streamlined systems of state aid.
Monti's high-level working group is due to present its findings at the end of the year, to be considered in time for revisions made to the budget expected in 2016.