Chalobah first appeared on the Blues bench at the age of 15 but almost six years to the day, he made his first appearance as Chelsea registered a 4-2 win over Leicester City in the EFL Cup.
The England Under-21 international is likely to remain on the fringes of the senior setup but he has acknowledged that representing the club was a dream come true.
The 21-year-old told Chelsea TV: "I'm over the moon, it's something I've dreamt about since I came to the club and I'm very happy that it's finally happened.
"The manager just said for me to concentrate on the pitch, make sure I'm switched on and do the defensive work because at the time it was 2-2."
Chalobah has previously spent loan spells at the likes of Watford, Middlesbrough and Napoli.