The 30-year-old Wuertz split last season between the Cubs and Triple-A Iowa, going 1-1 with a 3.63 earned run average in 45 games for Chicago.
Wuertz is 13-7 with one save and a 3.57 ERA in 265 relief outings since entering the majors with the Cubs in 2004.
Chicago also signed Japanese pitcher Ken Kadokura to a minor league contract with an invitation to spring training.
A 13-year veteran of the Nippon Professional Baseball League, Kadokura, 35, has gone 76-82 with a 4.36 ERA in 302 career games for the Chunichi Dragons (1996-99), Osaka Kintetsu Buffaloes (2000-03), Yokohama Bay Stars (2004-06) and Yomiuri Giants (2007-08).
The right-hander was a former teammate of Cubs right fielder Kosuke Fukudome while with Chunichi in 1999.