Rushden boss Justin Edinburgh told the club website: "I've known him from the time I worked at Wycombe scouting.
"I've seen him play and I think he certainly gives us that balance of the left footed player we've needed."
He added: "He comes with excellent references from people in the game and once we had the opportunity to bring him in I'm delighted to have sealed it and have him here with us.
Last season was disappointing, I got injured during pre-season, and after a change of manager it just didn't really work out from there
Rushden midfielder Lewwis Spence
"There were one or two League clubs showing an interest, but once he'd seen the football club and spoken to myself, he was delighted to come and join us."
Spence featured 33 times during his Adams Park spell, scoring twice, but finished last season on loan at Forest Green.
"The lads have all been welcoming, it's my first day of training but it's something to build on and I'm looking forward to it," he said.
"I'm a centre midfielder, up and down the field and I like to score goals now and again.
"Last season was disappointing, I got injured during pre-season, and after a change of manager it just didn't really work out from there, this year I've got a lot to prove to myself and the people that have doubted me."
Source: BBC Sport
Source: BBC Sport