The 24-year-old is yet to make an appearance for Mauricio Pochettino's side this season due to a thigh injury and is continuing to undergo his rehabilitation programme following a recent setback in training.
Over the last two season, Chalobah made a total of 63 appearances for the Blues across all competitions and has shown his versatility by operating at either centre-back and full-back.
However, following a significant spending spree by Chelsea co-owner Todd Boehly, it is thought that Chalobah may find it challenging to break into Pochettino's side an earn regular first-team football when he returns to full fitness.
Axel Disasi arrived at Stamford Bridge over the summer and has featured regularly in defence alongside Thiago Silva and Levi Colwill, who returned to the club following a loan spell last season.
Benoit Badiashile, Reece James, Malo Gusto, Marc Cucurella, Ben Chilwell and Ian Maatsen are other defensive options at Pochettino's disposal, while Wesley Fofana is not expected to return until the latter stages of the season as he continues to recover from an ACL injury.
Chalobah was heavily linked with summer exit from Chelsea before ultimately staying put in West London, but it is understood that the Blues have informed the defender that he is free to leave in January.
The Chelsea academy graduate could be one of the latest Englishman to swap the Premier League for the Bundesliga, as Bild claims that he has been offered the chance to sign for Dortmund in the New Year.
The report adds that head coach Edin Terzic and sporting director Sebastian Kehl are both keen to lure Chalobah to Germany after failing to sign fellow defender Armel Bella-Kotchap on loan in the summer.
It is thought that Chalobah, who is under contract at Stamford Bridge until June 2028, is most likely to leave Chelsea on an initial loan deal with an option to buy.
However, Chelsea could look to sell Chalobah in January as they allegedly have plans to recruit a new central defender in the winter window.
Inter Milan's Alessandro Bastoni is believed to be one name on Chelsea's radar, although they could face stern competition from a number of Premier League clubs including Manchester City.
The 24-year-old has been strongly linked with an exit from San Siro for some time, but interested suitors would have to fork out at least £60m if they are to stand a chance of winning the race for his signature.