The striker spent last season with the Milan club on a co-ownership deal that saw him score nine goals in 22 appearances, and it appears his play has convinced the Nerazzurri over a permanent move.
Sampdoria released a statement on their website announcing the deal.
“Mauro Icardi is now 100 per cent an Inter player,” the site read.
“Internazionale and Sampdoria have reached an agreement to terminate their co-ownership of the striker, who is now fully owned by Inter.”
The Argentine joined the Sampdoria Primavera squad on loan from Barcelona in 2011 and Sampdoria exercised his purchase option that summer after a successful campaign.
He scored 10 times for Sampdoria in the 2012-2013 season before Inter entered a co-ownership agreement in the summer of 2013 before acquiring for a total fee of €12 million.
Injuries cost him most of the first half of the season, but he was also the subject of frequent tabloid gossip for his relationship with ex-teammate Maxi Lopez’s ex-wife.