The Turin side were already two goals ahead when Ronaldo, the joint top scorer in Italy's top flight with 14 goals, saw his spot kick brilliantly saved by Stefano Sorrentino in the 52nd minute after Mattia Bani handled.
Juventus have 56 points from a possible 60 as they chase an eighth straight title. Bottom side Chievo have eight points.
The Flying Donkeys held out for only 13 minutes until Costa burst through the Chievo midfield and slipped a shot between two defenders from the edge of the area.
After missing his penalty, Ronaldo was frustrated twice more, turning the ball wide from Dybala's cross and then finding the side netting after the Argentine freed him on the left.
Juventus still added a third with a simple far post header from Rugani from Federico Bernardeschi's free kick in the 84th.