The Turkish champion announced on Sunday that personal terms had been agreed with the Netherlands international, and Unal has now confirmed that the star is due to arrive in Istanbul on Monday to complete his move.
"We are signing players according to our coach's directives," the 71-year-old told Galatasaray's official TV channel, GSTV. "It's a big achievement for Sneijder to play at Galatasaray.
"He said he is coming to end his career here. Our expectations won't be unfulfilled.
"[Inter president Massimo] Moratti is a real gentleman. I appreciated him every time we met. He did what he promised. In the end this is a happy ending for [all] three parties. I'm satisfied with Moratti's collaboration.
"I've explained our vision two years ago. We aimed to be in Europe permanently and that's what we are trying to do," he added.