FIFA wrote on its official website "Unexpected insertion", because the return of the European and English champions' playmaker was not expected before the start of 2024.
De Bruyne, 32, injured his thigh in the 1-0 Champions League final win over Inter in early June and bounced back during the first game of the current Premier League season against Burnley on August 11.
Since then, after undergoing surgery, the Belgium international has not returned to action as he was expected to return early next year rather than in December.
City will begin its first-ever participation in the Club World Cup, which starts on December 12, in the semi-finals against the winner of the match between Mexico's Leon, Concacaf champions Urawa and Asian champions Red Diamonds on Tuesday 19. If they come out victorious, they will play the final three days later.
The tournament also includes Auckland City of New Zealand, champions of Oceania, Al-Ahly of Egypt, champions of Africa, Fluminense of Brazil, champions of South America, and the Saudi Federation.
City coach Pep Guardiola said, quoting FIFA: "This tournament is very important and prestigious."
"It's not easy to qualify or win. We only need one (cup) to follow the winning streak and win all possible trophies for City."
"We're going to go there and prepare because it's a dream for us. The mood in the team is the best I remember in many years."
City achieved a historic treble last season by winning league titles, cup and Champions League, and later the European Super Cup on penalties against Sevilla in mid-August. While he failed to win the League Cup last season, he lost the Community Shield competition at the start of the 2023-2024 season.