The experienced Belgian international has signed a two-year deal with the Black Cats after arriving on Wearside on Tuesday to undergo his medical and put the finishing touches to his move.
The right-back becomes Sunderland's first signing of the summer, and Ghisolfi believes he'll be an important one.
Sunderland's director of football said: "We are delighted to welcome Thomas to Sunderland AFC - from the moment we started speaking, we felt he had a very positive feeling about the club.
"Throughout his career he has consistently performed at the highest level, representing some of Europe's biggest clubs, and Belgium on the international stage.
"He brings a wealth of experience, leadership, and professionalism, alongside real quality in both defensive and attacking phases of the game.
"Thomas is a player who understands what it takes to compete for success, and we're confident his mentality and character will have a positive influence on the squad.
"We believe he'll make an important contribution on and off the pitch, and we're excited to see him begin this new chapter with us. It feels like a great fit."
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Meunier is currently on an end-of-season break having represented Belgium at the World Cup, with his three appearances taking his tally of international caps to 83.
He will link up with the Sunderland squad early next month.
Meunier said: "I am hugely excited and honoured to join Sunderland.
"I'm very happy to be here and to begin this new chapter in my career. The Premier League is one of the most competitive and exciting leagues in the world, and it's a challenge I've wanted to experience.
"When I spoke with the club, I was impressed by the ambition, the project, and the desire to keep moving forward.
"Competing in Europe was also a big factor in my decision because, as a player, you always want to test yourself against the best teams and compete for trophies."
Meunier, who will wear the number 12 shirt for the Black Cats, added: "I hope I can bring my experience to the squad, both on and off the pitch.
"I've been fortunate to play in some fantastic teams throughout my career, and now I'm looking forward to giving everything for this club, helping my team-mates, and building a strong connection with the supporters.
"I can't wait to get started, meet everyone, and play my first match in front of the fans."