Reading and Sheffield Wednesday are looking to bolster their attacking options in this month's transfer window and they have been impressed by Clarke-Harris.
The talented 21-year-old has scored six goals for a struggling Rotherham side so far this season and his performances for the Millers have brought him to the attention of a number of clubs.
Rotherham broke their transfer record to sign Clarke-Harris from Oldham Athletic in the summer of 2014 with the striker regarded as one of the best young talents in the country.
Clarke-Harris endured a difficult first season at Rotherham, spending two spells out on loan at MK Dons and Doncaster Rovers, but he is now beginning to fulfil his undoubted potential.
Reading are in the market for a new striker after losing Nick Blackman to Derby, while Sheffield Wednesday lost out in the race for Blackman meaning both clubs are targeting a move for Clarke-Harris.
Rotherham are reluctant to lose Clarke-Harris this month as they battle to stay up in the Championship, but they are bracing themselves for interest in their prize asset.