The Blues have won four in a row and extended the NHL's largest point total to 95.
Atkinson's goal 2:24 into the second created a 1-1 tie but St. Louis dominated from that point.
Chris Stewart put the Blues in front with a backhander midway through the second and T.J. Oshie added a power-play goal with 5:22 to go in the middle period.
Alex Pietrangelo tacked on a goal in the third period, that one also coming on the power play.
It was the 29th home win of the season for the Blues, tops in the league. They have lost on their home ice just eight times, four of those setbacks coming in overtime.
Curtis Sanford stopped 25 shots in taking the loss.