Cresswell, 19 impressed Millers boss Mark Robins when he played for the Blades reserves at Millmoor on 5th September in a 1-1 draw.
He was signed last Friday by the Millmoor club and was an unused substitute in the League Two home draw with Nott's County.
"He has come in as an emergency loan because Ian Sharps is out and Ryan will give us that bit of cover," Robins told BBC Radio Sheffield.
Meanwhile Sheffield United have completed the free transfer of Brazilian born defender Zé Maria who has made over 40 appearances for his Country. He may play for the Blades in their Carling Cup tie with Morcambe on Tuesday night.