The club’s former midfielder is back at Aggborough after a deal was struck with York City.
Penn returns nearly a decade after leaving the club but when he was offered another chance he couldn’t say no.
“It has been a long week but it’s great to get it done,” said the former Gateshead man after completing his paperwork.
“When an agreement was reached with York I talked to my family and we decided we had to come back to Kidderminster.
“I am delighted to be back at the club and hopefully we can go on and achieve something this season.”
Penn left Harriers in 2009 and the club are very much in the title race in the National League North.
He could make his second debut for the club on Saturday when they take on struggling Nuneaton Borough.