Frijns and his team executed a perfect race strategy, switching from the soft tyres to the hard compound at the first opportunity on lap six.
Thanks to a fast stop, this gave him track position over everyone save for poleman, and early leader, Marcus Ericsson of DAMS.
But when the frontrunners tripped over cars on the divergent strategy of a long first stint on the hard tyre, Frijns grabbed the virtual lead as Ericsson collided with Sam Bird's Russian Time car. Ericsson was forced to retire as a result of the damage.
Frijns then did a perfect job of managing his tyres and the traffic, and kept his cool when second place Jolyon Palmer got to within 0.7 seconds of him with 10 laps remaining.
In the final laps, Frijns proved he had pace to burn, extending an eventual 3.3s margin of victory over Felipe Nasr, who bounced back from a terrible start to finish second after passing Carlin team-mate Palmer, with contact, at turn three with four laps to go.
Palmer hung on to finish third after what he admitted was "a crazy race", but is under investigation from stewards for pushing Bird onto the grass exiting Turn 4, which caused Bird to spin into retirement during the frantic battle.
Series returnee Jon Lancaster made it a double celebration for Hilmer with fourth place, ahead of points leader Stefano Coletti and Tom Dillmann.
Dillmann went for a hard/hard-tyre strategy, and could have finished on the podium but for running wide at Turn 3 on the final lap. He earlier escaped when Nathanael Berthon flew over the back of his car and Sergio Canamasas at Turn 10.
Championship frontrunner Fabio Leimer had a disastrous race, finishing 18th after being forced to pit for a new front wing after a startline clash with James Calado, which put the Briton out on the opening lap.
To compound a miserable race for DAMS, following the reigning champion team's front-row lock-out, Stephane Richelmi trailed home 15th after a drive-through penalty for punting Dillmann into a spin at turn four.
- Sports & Recreation
- Jolyon Palmer
- Marcus Ericsson
- Sam Bird