The 27-year-old towering defender is the older brother of United striker Mark Jones and put pen-to-paper late on Friday after leaving the Zecco Stadium earlier in the day.
Jones, who is the Evo-Stik Northern Premier League Premier Division side`s reigning three-time player of the year, is expected to make his United debut on Saturday in the Pilgrims’ home fixture against Alfreton Town — with Carl Piergianni (suspension) and Zak Mills (hamstring injury) sidelined.
Leaving The Jakemans Stadium, meanwhile, is 23-year-old midfielder Jay Dowie, who has joined National League South side Concord Rangers on a permanent basis.
Shefford-based Dowie made twenty-six appearances in two spells with the Pilgrims.