The Norwegian teenager is the Blues’ first signing, since Frank Lampard became manager and their transfer ban was lifted.
Fiabema, who has represented Norway at Under-17 level, only made his professional debut in July against FK Haugesund.
The 16-year-old impressed during a trial at Chelsea’s Cobham Training Centre, alongside compatriot Christos Zafeiris, who currently plays for Valerenga.
It is unknown whether Zafeiris will be signed, but a deal has now been secured to sign Fiabema.
He will join the club’s academy system and work under coaches Andy Myers and Ed Brand.
