The Nerazzurri have confirmed that the Argentina striker has completed his move to San Siro after they ended their co-ownership agreement with Sampdoria
The 21-year-old enjoyed an impressive season for Walter Mazzarri's men in 2013-14, scoring nine goals in 22 Serie A appearances as the Nerazzurri secured a fifth-placed finish.
The Argentine has been the subject of rumoured interest from Atletico and Real Madrid in recent months but has consistently expressed his desire to remain at San Siro.
"FC Internazionale and U.S. Sampdoria have reached an agreement to terminate their co-ownership of the striker [Icardi], who is now fully owned by Inter," the club announced on their official website on Tuesday.
Icardi joined Inter in August 2013 as part of a co-ownership agreement, after netting 11 in 33 games for i Blucerchiati and has one senior international cap to his name after featuring in Argentina's 3-2 World Cup qualifying defeat against Uruguay last October.