The new terms have removed any release clauses put into the Norwegian's last contract, which had an expiry date of June 2027.
The extension is said to be one of the most lucrative contracts in sporting history, according to The Athletic.
"I am really happy to have signed my new contract and to be able to look forward to spending even more time at this great club," Haaland said.
"Manchester City is a special club, full of fantastic people with amazing supporters and it's the type of environment that helps bring the best out of everybody."
Haaland joined City in 2022 from Borussia Dortmund and has cemented himself as one of the deadliest strikers in the world under Pep Guardiola.
The Norwegian has netted 111 goals in 126 games for the club alongside winning two Premier League titles, the Champions League, FA Cup and Super Cup.
"I also want to thank Pep, his coaching staff, my teammates and everyone at the Club as they have all helped me so much in the past couple of years. They have made this such a special place to be and now I am City no matter what," Haaland added.
"I want to keep developing, keep working to get better and look to do my best to try and help us achieve more success going forward."
Haaland has scored 16 times in the league this season, but it has been a challenging campaign for him and his City teammates.
City sit sixth in the Premier League – 12 points off leaders Liverpool – and recently endured a shocking run of one win in 13 games across all competitions.
Guardiola's side are also hovering just inside the play-off line in the league phase of the Champions League with two games left to play.