"Coming here I have had a wonderful impression, even of the Milanello training complex," the 27-year-old told Sky Sports 24. "All players would like to train here and I'm happy to have joined AC Milan.
"It was not easy, I arrived on deadline day, but the group has welcomed me very well and I am very happy of that. AC Milan is in a transition season because some of the best players were sold and many veterans are gone.
"We have a young team that should be rebuilt but I am proud to be part of this project and I want to contribute to future successes. Watching the AC Milan of the '80s and early '90s I dreamed of playing here."
De Jong, who has signed a three-year contract with the Rossoneri, made his Serie A debut as a first-half substitute in place of Riccardo Montolivo during Saturday's 3-1 win over Bologna.