Lega Serie A have confirmed that the Chilean has finally completed his move to San Siro, having been training with his new team-mates for the past few days
The 27-year-old spent just one year with the Welsh side after signing from Sevilla for a fee of £10.8m (€13.5m), the club suffering relegation during his sole campaign there.
After playing a key role in his country's impressive World Cup campaign this summer, Medel has been consistently linked with a move to San Siro.
He has been training with the Serie A side for the past few days, linking up with them during pre-season and Lega Serie A have now confirmed that he has completed his move to the Nerazzurri.
"In pre-season, I have not worked a lot because of a leg injury," he said upon his arrival at training.
"But I am hoping to be ready in time for the start of the new season. I'm glad to be here. Forze Inter!"
Medel, a veteran of 61 international appearances, began his career with Universidad Catolica in his hometown of Santiago, before winning a move to Boca Juniors in 2009.
He spent two years in Buenos Aires before winning his first move to Europe, spending another two campaigns in Andalusia before his move to the Premier League.