Sassoli, 65, died around 1.15 a.m. (0015 GMT), according to his spokesperson, Roberto Cuillo.
According to his office, Sassoli, an Italian socialist and former journalist from Florence, was hospitalized last month owing to a “severe issue” with his immune system.
Since 2019, he has presided over the 705-seat parliament.
In his inauguration address, Sassoli encouraged Europeans to combat the “virus” of radical nationalism by reforming EU migration and political asylum policies.
His time in the primarily ceremonial capacity was set to expire this month.
He had been unable to chair the Strasbourg-based parliament in recent weeks due to sickness, and he had also missed the European Commission’s annual state of the union event in September.
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