The team announced the deal on Tuesday, and it's worth $600,000, plus bonus incentives.
The Blues also signed goaltender Ben Bishop to a one-year, two-way contract worth $600,000 (NHL) and $105,000 (AHL). The 6-foot-7, 215-pound Bishop, who is from suburban St. Louis, is expected to compete for the backup spot behind Jaroslav Halak.
The 36-year-old Nichol spent last season with the San Jose Sharks, dressing in 56 games and picking up four goals and three assists. The 5-foot-9, 180-pound center is an 11-year NHL veteran with 52 career goals and 66 assists.
The 24-year-old Bishop was 3-4 with a 2.76 goals-against average and .899 save percentage last season with the Blues. He spent most of last season at Peoria, Ill., of the AHL, going 17-14-2 with a 2.55 GAA. Bishop was a third-round pick of the Blues in the 2005 draft.