The 27-year-old said that it was always his intention to return to Inter and now wants to do well for new coach Walter Mazzarri.
"For me it's a homecoming," Andreolli told reporters. "I remember the day I left, I was really sad to be leaving Inter and it's great to be back after so many years.
"I have improved and I have a real sense of pride to be back here. I always wanted to come back and have worked hard for it.
"I have been struck by [Mazzarri's] will and determination. Also, I would like to emphasise the desire of the champions in the squad. They all have the desire to improve and are the leaders of the group."
Inter finished a disappointing ninth in Serie A last season.