The 32-year-old from Twickenham drops down from the Football League after three-years with Stevenage as Luke Garrard continues to build for the 2017/18 campaign.
Wells began his career in the academy at Brentford, but made just one appearances before joining non-league Hampton & Richmond Borough.
The defender climbed his way back up the divisions through spells at Staines Town and Braintree before being signed by League Two side Stevenage for a reported £25,000.
The 32-year-old said that Boreham Wood provided the perfect next step in his career, he told the official club website: “It all fitted in nicely and I will be doing a bit of coaching in the academy as well which helped.
“I will also be able to start the college course that I wanted to with the days off that I will get, so I will be doing something that I love, while still playing football.
“I had a chat with the manager and the Chairman and the direction that they are going in and the amount of time and effort that they seem to put in to the place convinced me.”
The experienced defender told supporters that he has still got plenty to offer, he continued: “I will bring a bit of experience into the team and I reckon I have still got two, or three good years in me.
Wood manager Garrard believes that the signings of Wells and Murtagh prove that his side can compete with the best in the division in the transfer market.
“Kieran and Dean will bring added quality and experience at this level, and I think that the pair of them will only boost what we have at the club,” the 31-year-old stated.
“Dean himself will bring an experience, an understanding and a leadership because he has been in the game a long time.
“He has played at this level with successful teams already and I honestly believe that he will compliment what we already have at the back.”