The Brazil international joined the Nerazzurri from Lazio on deadline day for a fee of around 20 million euros, ending a four-year spell in the capital.
The 28-year-old has already set his sights on ending a three-year trophy drought at Inter, which is without a major title since claiming the Coppa Italia in 2011.
"I'm very happy to be here, to be part of Inter,” Hernanes told Sky Italia. “I expect a challenge and I am ready. [My dream] is to do well, the image I have of Inter a team that has won everything and I hope to help them back to that level."