The 33-year-old will conclude his decade long Man City career once his contract expires at the end of the season.
De Bruyne has been a key player for Pep Guardiola’s side throughout his tenure, helping them win six Premier Leagues, five League Cups, two FA Cups, and a Champions League, among others.
In an interview with ESPN, Gundogen, 34, was full of praise for the Belgian, suggesting he’s the best player in the club’s history.
He said: "He's irreplaceable. We know that no one will just come and be a replacement for him. Of course it will be covered somehow. The club always does that.
"What Kev has done for the club is unbelievable. For me personally, in the history of Man City, there is no better player than Kevin De Bruyne. It's been a pleasure for me to share a pitch with him for such a long time.
"I've had that connection with him off the pitch so it's been a privilege to get to know him and his family."