The gifted midfielder, who is seen as one of Europe's biggest talents, will continue his career in Serie A after passing the obligatory medical checksDinamo Zagreb youngster Mateo Kovacic has completed his transfer to Inter after passing his medical on Thursday.
The Croatian champions announced on Wednesday that the midfielder would leave the club for the Nerazzurri after both sides had reached an agreement over a fee believed to be in the region of €11 million, which could rise to €15m.
Kovacic visited the Policlinico San Matteo di Pavia on Thursday for his medical, and the physical examination did not bring any noteworthy issues to the fore.
"Joining Inter is like a dream come true. I do not know how to explain it. I can only say that it is an incredible feeling and that I will do my utmost for the club," the player told Inter Channel.
"When I was still a boy, Inter were winning lots of trophies. I was training and taking part in campuses and Inter were an important team for me.
"They're one of the biggest clubs in Europe and Italy. I'm happy. I've joined a team like this and I hope to stay here for a long time.
"There are lots of great players here, like [Antonio] Cassano and [Fredy] Guarin for example. I hope to be able to do my bit and help Inter in the championship.
"For now all I can do is thank [the fans] and I hope to meet them soon."
The 18-year-old has inked a contract until the summer of 2017 with Inter.