The 27-year-old Denmark midfielder has signed a contract until 30 June 2024.
"I'm very excited and can't wait to introduce myself to the fans," Eriksen said. "I've already experienced their warmth, it's been a fantastic welcome. I feel great."
"The numbers say that I did really well in England. It's now time to start a new challenge, I'm really happy to have the opportunity to play in Serie A for a big team. Inter is a fantastic club."