The midfielder has a key player for the Premier League club since moving from Norwich City in June 2018.
Manchester United is among the clubs related to the 23-year-old, whose previous contract lasted until 2023, but has committed to his long career with the Foxes.
“I am very pleased to sign a new contract for this football club,” Maddison told Leicester’s official website. “It’s an incredibly exciting time to be a Leicester City player with so many things going on and off the court and I’m extremely happy to be a part of that.
A new four-year contract for Madders10! ? pic.twitter.com/JwAZITjIUs
“What we have achieved as a club this season is a big step forward for us and I know there is much more to come from this team.
“I have enjoyed every moment since I arrived in Leicester City. The enthusiasts have been amazing to me and we have a fantastic group of players in this locker room who are determined to show what we are able to do in combination in Europe and Europe. Premier League next season.”
Maddison has scored 16 goals in matches with Leicester and made his England debut against Montenegro last year.
He named Leicester’s young player of the season for the 2018-19 season.
Maddison will play in the Europa League next season after Brendan Rodgers recently lost a spot in the Champions League, completing fifth.