The Foxes looked in control through the contest at King Power Stadium and deserved to take all three points.
Frank Lampard made the surprising decision to start Mason Mount and Kai Havertz on either side of Mateo Kovacic in midfield.
The Nigerian's left-footed strike from the edge of the box crashed off the post and past the helpless Edouard Mendy.
Lampard's side thought they had a penalty when Jonny Evans brought down Christian Pulisic, but VAR ruled the foul was outside of the box.
Mount hoicked the resulting free-kick over the bar and Leicester went down the other end to make it 2-0.
The Blues pushed hard in the second-half and came close to getting one back when substitute Timo Werner poked home Hakim Ziyech's free-kick, only for the offside flag to be raised.
The result is doubly sweet for Foxes boss Brendan Rodgers. It was his first win over his former employers and it takes Leicester above Manchester United on top of the table, although the Red Devils have a game in hand.
After 19 games, the 2020/21 season is the second worst in the Premier League during Roman Abramovich's 18-year ownership of the west London club.