Frijns, points leader going into the event, collided with Bianchi at Turn 4 on lap 21, leaving the Ferrari protege in the gravel. Bianchi had just overtaken Frijns for fourth place earlier in the lap.
Fortec driver Frijns went on to finish seventh on the road, but the penalty - awarded in lieu of an in-race drive-through - dropped him to 14th.
However as he was already ahead in the points before the finale, Frijns keeps the 2012 title. The Dutchman came into FR3.5 this year as a rookie, having won the Formula BMW Europe and Formula Renault 2.0 Eurocup championships in the preceding two seasons.
The penalty decision was only reached after several hours of deliberation by the stewards.
Although the drivers' championship is unaffected by the penalty, Frijns' demotion means his Fortec team falls behind Arden Caterham to third in the teams' standings, as the latter scores second in its debut FR3.5 season.