Bradley Garmston has signed a three-year contract to return to Gillingham on a permanent basis.
The defender had a loan spell with the League One side last season, and was available on a free transfer after being released by West Bromwich Albion at the end of the campaign.
Manager Justin Edinburgh told the club's website: "I'm very happy to have secured Bradley on a three year deal, he was impressive during his loan spell with us and I have no doubt he will be a valuable asset to us now he's with us permanently.
"He's a left-back who is just as good getting forward as he is defending and I look forward to working with him during pre-season and beyond."
Garmston made nine appearances for Gillingham before returning to The Hawthorns in February with an injury.