Coventry had gone ahead in the 24th minute when Dele Adebola crossed for Gary McSheffrey to fire a well-struck shot past Foxes keeper Robert Douglas.
De Vries headed in Momo Sylla's corner a minute after the interval, while Joey Gudjonsson and Dion Dublin were both foiled by visiting keeper Clayton Ince.
Coventry boss Micky Adams:
"We started well, but we allowed Leicester to turn it into their game and we didn't seem able to get a foot on the ball.
"We don't seem able to defend well at set pieces, and I can't understand that as we are big enough at the back.
"Gary McSheffrey had a shout for one penalty but he claims on both occasions he was clipped by their keeper."
Leicester: Douglas, Stearman, McCarthy, Dublin, Johansson, Sylla, Gudjonsson, Kisnorbo, Hamill (Tiatto 82), Hume (Hammond 87), de Vries.
Subs Not Used: Henderson, Maybury, Gerrbrand.
Booked: Gudjonsson, Sylla.
Goals: de Vries 45, 46.
Coventry: Ince, Duffy (Whing 66), Heath, Shaw, Hall, Nalis (Morrell 67), Hughes, Doyle, Adebola, McSheffrey, Scowcroft.
Subs Not Used: Tuffey, Watson, Impey.
Booked: McSheffrey, Scowcroft.
Goals: McSheffrey 24.
Ref: K Wright (Cambridgeshire).