Gavin Rae moved through the middle in the tenth minute but his low shot was easily gathered by Blackpool keeper Paul Rachubka.
The Bluebirds were having the better of the opening exchanges and were passing the ball around with speed. Jay Bothroyd was in the thick of the action, but too many times the final ball let them down.
A burst by Joe Ledley almost set up McCormack but the Scot was inches away from sliding the cross home.
Blackpool tried to hit City on the break, but were forced to shoot from distance and rarely troubled home keeper Tom Heaton.
Gary Taylor-Fletcher did much better on the half hour with a rasping shot that Heaton could only push away.
Three minutes before the break Bothroyd sent McCormack scurrying in on goal, but the visiting defence were back in numbers to clear the danger.
Blackpool began the second half on top but after Whittingham replaced Comminges in the 55th minute it sparked City into life.
The former Aston Villa midfielder had two strikes on goal but could keep neither down and the opportunities were lost.
Ian Evatt stuck out a leg to stop a goa-bound shot from McCormack as City pressed for that important goal.
Another fleeting chance fell to Bothroyd in the 70th minute, but once again his shot flew high over the bar.
Blackpool forced a couple of corners but Darren Purse was superb in defence heading clear twice when Heaton was under pressure.
The breakthrough came in the 83rd minute when the impressive Bothroyd crossed and Whittingham headed into the corner.
Three minutes later McCormack crashed a 25-yard free-kick home for his tenth league goal of the season to give City victory.