Worley becomes the second Foxes player to sign on loan at the Alex, following the signing of midfielder Aman Verma who signed on a three-month loan.
The Lymm born defender started his career with Cheshire neighbours Stockport County and was snapped up by Premiership giants Chelsea for a fee of £150k which was settled by a tribunal.
Worley then spent three-years at Chelsea but failed to make an appearance for the Blues, although he was loaned out to Doncaster Rovers, Carlisle United and then Leicester City in 2008 where at the end of the season he signed a three-year contract with the Foxes.
Worley failed to make an apperance for the League One Champions last season but was loaned out to Luton Town from September to November 2008 making ten appearances for the Hatters.
Crewe manager Gudjon Thordarson could not hide his delight with the signing of Worley, he told the official Crewe website "I am both delighted and relived to have finally got Harry in on loan. He is a player I have tracked for a while and I had tried to bring him in on a permanent basis in the summer but that fell through.
"When Nigel said he would be available on loan then I was delighted to bring him here. He is here until January and then we will assess our options. We may look to extend the deal then until the end of the season.
"Harry is 6'3" and has a physical presence. He is young in terms of his age but does have league experience. He is the sort of player who is committed and won't be afraid to put his head in where it hurts."