Cork has just returned to this country from Malaysia where he captained Chelsea's under-19 team in the World Youth Club Championships.
"He also went to America with the Chelsea first team squad for their pre-season tour and came on as a replacement for Frank Lampard," United manager Nigel Adkins told the Scunthorpe Telegraph.
"We have brought him here to play football and know he is match-fit, but we won't know how jet-lagged he is until he gets here today because he has been doing a lot of travelling.
"Jack is a player we targeted towards the end of last season and is one of the players we have pursued patiently and quietly throughout the summer.
"We are delighted that Chelsea want him to continue his development here at Scunthorpe.
"He is a defensive midfield player who has a good range of passing."