The defender is the club's longest-serving player after signing from Mansfield Town in 2004.
"It's a good honour for myself," the 31-year-old told the club's official website.
"It's not going to be team captain as such but club captain where I will go round and do various stuff for the lads, so just a link between the manager and the players.
"I think my job around the place is to be a good example to the young lads and speak to them when I can," he added.
The Tykes kick off their Championship campaign away at Nottingham Forest on Saturday, August 6.