The 36-year-old forward scored four points (one goal, three assists) in 17 regular-season games and did not score a point in two Stanley Cup Playoff games with the Nashville Predators last season.
Richardson helped the Los Angeles Kings win the Stanley Cup in 2012, when they were coached by Flames coach Darryl Sutter.
Selected by the Colorado Avalanche in the fifth round (No. 163) of the 2003 NHL Draft, Richardson has scored 246 points (107 goals, 139 assists) in 825 regular-season games with the Avalanche, Kings, Vancouver Canucks, Arizona Coyotes and Predators, and 13 points (seven goals, six assists) in 61 Stanley Cup Playoff games.
The Flames signed restricted free agent defenseman Connor Mackey to a two-year, $1.825 million contract ($912,500 average annual value) on Wednesday. The 24-year-old made his NHL debut Feb. 13 for Calgary against the Vancouver Canucks, and he scored three points (one goal, two assists) in six games.
