The Foxes have confirmed that Ndidi has agreed personal terms, passed a medical and has signed a contract with the club, pending a work permit.
Nigerian defensive midfielder Ndidi, 20, has penned a five-and-a-half-year contract until the summer of 2022.
It is understood that reigning Premier League champions Leicester will pay Belgian club Genk up to £15million for the signature of Ndidi.
"The Nigerian international midfielder, 20, has agreed personal terms, undergone a medical and will sign a contract to June 2022 once a work permit has officially been granted. He will wear City's no.25 shirt.
"Ndidi is expected to complete the formalities of his move to Leicester City later this week."