CFG, which owns the Premier League champions, has bought the Chengdu-based side as part of a joint-purchase deal involving China Sports Capital and robotics firm UBTECH.
City chief executive Ferran Soriano said in a statement on Wednesday: "Today marks an exciting new chapter in the growth of City Football Group. China is an extremely important football market, which we have been focused on for some time.
"We believe strongly in the future of football in China. We are making a long-term, sustainable commitment to grow and develop Sichuan Jiuniu FC and to nurture Chinese footballing talent. These objectives are equally important.
"Our immediate focus will be strengthening our football performance, using all of our experience and know-how, forging a strong relationship with our fans and building a strong presence in the community."
Sichuan Jiuniu become the seventh club to join CFG's global conglomerate.
China Sports Capital has held shares in CFG since December 2015, while UBTECH has been one of City's commercial partners since 2016.
Pep Guardiola's side are considered one of the favourites to win the competition and will be confident of progression against the side who are currently 14th in the Bundesliga table.
The Premier League champions are still fighting to win four titles in the 2018-19 campaign, with City currently joint top of England's top flight, while they face Chelsea in the Carabao Cup final on Sunday.
Despite being in with a chance of winning a quadruple this season, Kevin De Bruyne is adamant that City are just focused on winning games, rather than worrying about how many trophies they might collect.
He told reporters: "I think the goal is not to win the four competitions; the goal is to win every game and, the further you progress, you want to win the next game. On Sunday we can win the competition but you cannot say at the beginning we are going to win four.
We are happy with where we are, we want to progress to the quarter-finals [in the Champions League] and be closer to winning it. But to win all four and set that standard is nearly impossible."