The 21-year-old becomes manager Mark Yates' third summer signing after penning a a two-year deal at Aggborough.
Bignot is no stranger to Kidderminster having enjoyed a brief loan spell with them last season, making three first-team appearances before being recalled by Crewe boss Dario Gradi.
"We're delighted to have Paul on board, he's an exceptional defender and I'm sure he'll be a great asset for us," Yates told the official Kidderminster Harriers website.
"He comes from a great footballing background at Crewe and we know what he's all about. He can and has played at a higher level and I'm sure he can only keep getting better."
Source: http://www.confguide.com/newsArticle.do?id=6692