The 29-year-old, released by the Glovers at the end of the season, has agreed a two-year contract at Home Park.
Manager John Sheridan has also added Sean McCarthy and John Harbin to his backroom staff.
Former Argyle striker McCarthy returns to the club as first-team coach and veteran Australian coach Harbin has been named performance manager.
Sheridan told the club website: "I am very pleased to get my backroom staff sorted out.
"There is a lot of very valuable experience there - people who have played at the highest level and have coached at the highest level.
"We are now well set up to be able to get the best out of the players.