The Blues are looking for buyers in the English Championship after he was left out of squad numbers for the ongoing season.
Watford and Middlesbrough are the two leading clubs keeping tabs on the Ghana international.
Rahman is back at Chelsea after ending his loan spell at Spanish side Real Mallorca.
With the transfer window in England still opened until October 16, the left-back could secure a move to any of the Championship side before the window is shut.
The Ghana international joined Chelsea in a high-profile move back in 2015 but made just 23 appearances in five-years.
He has been shipped out on loan on four occasions, including two spells at German side Schalke, one at French outfit Reims and lately Real Mallorca.