The ex-Colchester trainee, 28, follows the same route taken by Braintree team-mate Kenny Davis just a fortnight ago.
Both were in the Iron side who finished a club-best third, only to be beaten by Grimsby Town after extra time in the promotion semi-finals.
"We had a talented squad, but we need additional leaders to help get us over the line," said boss Luke Garrard.
"In Painey, Kenny Davis, who we signed a few weeks ago, and with the likes of Joe Devera, Dave Stephens, Danny Woodards, Ben Nunn and Conor Clifford, that problem will now solve itself."
"I'm delighted to secure Matt. His experience, ability and versatility will serve us well. It's a signature that I've targeted since the season came to an end and I'm again very grateful to our chairman for backing me on this."
Paine, who can also play centre midfield, made 183 non-league top-flight appearances for Braintree over the past five years.
He is Boreham Wood's third summer signing, following Davis and winger Bruno Andrade from Woking.
Boreham Wood have signed experienced defender Matt Paine from fellow National League side Braintree Town.