The 35-year-old Immobile is due to undergo a medical on Sunday, giving Paris FC a proven top-flight goalscorer after Dzeko opted to move to Schalke last week.
Immobile has been limited to nine appearances for Bologna this season because of a thigh injury. He returned to Serie A in the summer after a year at Besiktas.
He shares the record for most goals in a Serie A season, scoring 36 times for Lazio in 2019-20 to equal the mark set by Gonzalo Higuain four years earlier.
Immobile, a Euro 2020 winner with Italy, is Lazio’s all-time leading scorer with 207 goals in 340 games.
He has 17 goals in 57 caps at international level but has not played for Italy in over two years.