Thorley began his career at Stoke City before moving to Stafford Rangers in 2009.
He has since had lengthy spells at Worcester City, Hednesford and Rushall Olympic.
Thorley tasted disappointment last season when Rushall lost to Coalville Town in the Southern Central Division play-off semi-finals.
Blues manager Neil Baker said: "Tom is a great signing for Leek Town and will add quality, depth and competition in our already very good midfield.
“We secured his services over several other local clubs who wanted to sign him."
Thorley said: "I'm delighted to sign for Leek. I know quite a few of the lads, who have made me really welcome already.
“They play attractive football and are looking to progress further, which is a big part of the reason for signing."
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