The Chelsea academy graduate has earned himself a spot in the senior team in recent weeks and made the matchday squad against Bournemouth over the weekend.
Despite not featuring off the bench at the Vitality Stadium, Mauricio Pochettino did get a look at Gilchrist in pre-season having given him some game time on The Blues' tour of the United States.
Chelsea have now tied down the 19-year-old to a new contract that will see him remain at Stamford Bridge until June 2025, with the option of a further year on top of that.
Gilchrist was reportedly on the radar of newly-promoted Sheffield United, who were keen on a permanent move for the Chelsea Under-21 captain during the summer.
However, while Gilchrist has committed his immediate future to Chelsea, a loan move to gain regular game time in January does remain a possibility.
Coming from a Chelsea-supporting family, the defender joined The Blues as an Under-11 player and put pen to paper on his first professional contract in the 2020-21 season.
Gilchrist was nominated for the PL2 Player of the Year last season and has made four appearances for Chelsea Under-21s this term with a record of two wins and two losses.