Town confirmed earlier in the week that talks were ongoing, and a deal has now been agreed.
The fee is unlikely to be a sizeable one, due to Lazio`s current financial plight, but finally removing Sereni`s salary from the wage bill will come as a relief to Ipswich.
Town, who have secured a 50 percent sell-on fee plus two future friendlies with Lazio, are now looking to draw a line under the affair.
"Matteo has made it clear that he didn't want to play for the club any more and saw his future back in Italy," Town boss Joe Royle told the club`s website.
"The move has dragged on a bit and I`m glad the episode looks like it is coming to a close.
"I`m sure the move will work out best for all concerned."
