The 21-year-old arrived in West Yorkshire on Thursday morning for further talks with the Championship leaders as he looks set to again depart Stamford Bridge.
He joined Brighton on a temporary deal last season, but made just 13 appearances for the Seagulls before an anterior cruciate ligament injuy ended his spell with Chris Hughton's side in January.
The England Under-20 international is still working his way back to full fitness following that injury and chose to leave his decision to make any loan move until the end of the transfer window so he could continue his rehabilitation at Chelsea's Cobham training ground.
He is now set to join up with Marcelo Bielsa's side, though, with the Argentine coach looking to add competition for places in his midfield ranks.
Bielsa has overseen an encouraging start to the season at Elland Road, with the Whites sat atop of the Championship table having won four of their first five league games of the season.
They host second-placed Middlesbrough on Friday in an early-season clash of potential promotion chasers, with Tony Pulis' side level with Leeds on 13 points.
Brown will become the third Chelsea loanee in Bielsa's squad this season, with Lewis Baker and Jamal Blackman already bedded in at Leeds following moves earlier in the summer window.
Meanwhile, young Chelsea striker Ike Ugbo has completed a loan move to Scunthorpe United, as reported by Goal earlier in the month.
Ugbo spent last season on loan at Barnsley and has now moved to Glanford Park until January as new manager Stuart McCall bolsters his squad late in the transfer window.