The 28-year-old Italian has left Anfield bringing an end to a frustrating three-year spell at the club, during which he failed to make himself a regular
After signing for the Merseyside-based club back in 2009, Aquilani has since made just 18 league appearances after costing Rafael Benitez a fee in the region of 17 million pounds.
However, a move has been on the cards for some time after the player was flown back early from the club's pre-season tour of North America to help force through the switch, with Delle Valle claiming a deal has been struck.
"We have bought Aquilani," Della Valle told reporters at Fiorentina's pre-season training camp in Moena.
It was originally thought that under new management, with Brendan Rodgers now at the helm, the Italian would be granted more first-team opportunities after spending the last two seasons out on loan with AC Milan and Juventus, but he has since been deemed surplus to requirements.
It represents the latest move in Rodgers' re-shaping of the squad since taking over the reins this summer from predecessor Kenny Dalglish, with striker Andy Carroll's future also up in the air.
The former Swansea boss has already openly stated that the club is considering moves for both Swansea's Joe Allen and Fulham's Clint Dempsey this summer as well as admitting Carroll could depart Anfield.