Sainz made a clean getaway to leave fellow front row starter Marlon Stockinger behind at the off, and from there he set about building a lead that was more than 10 seconds by the chequered flag.
Stockinger spent the entire race keeping Sauber F1 reserve Sergey Sirotkin at bay after the Russian had picked his way through some slow starters.
Sirotkin was never quite close enough to mount an attack for second, and by the end of the race Stockinger had stretched out a small margin of safety to secure his second position.
Formula Renault 2.0 graduate Luca Ghiotto took a comfortable fourth ahead of Pierre Gasly, who survived a battle with Jazeman Jaafar to complete the top five.
Jaafar briefly got ahead of the Red Bull junior early on, but he had to concede the position as he had gained ground by cutting the second chicane when trying to pass Gasly.
After that the Malaysian was never quite able to mount another challenge, and in the closing stages he lost out to a charging Nikolay Martsenko for sixth place.
Further back, the points positions were completed by Oliver Rowland, who recovered to 10th place having started from the pitlane when his car failed to get away for the formation lap.
Race one winner Will Stevens, who struggled in qualifying, retired from race two after colliding with Will Buller while they battled over ninth place.
Results - 27 laps: Pos Driver Team Time/Gap 1. Carlos Sainz Jr DAMS 43m10.774s 2. Marlon Stockinger Lotus +10.835s 3. Sergey Sirotkin Fortec +12.524s 4. Luca Ghiotto Draco +19.137s 5. Pierre Gasly Arden +20.178s 6. Jazeman Jaafar ISR +28.477s 7. Nikolay Martsenko Comtec Racing +30.014s 8. Pietro Fantin Draco +33.845s 9. Roberto Merhi Zeta Corse +36.393s 10. Oliver Rowland Fortec +36.959s 11. Norman Nato DAMS +41.465s 12. Matias Laine Strakka +53.086s 13. Zoel Amberg AV Formula +54.792s 14. Oliver Webb Zeta Corse +59.383s 15. Roman Mavlanov Zeta Corse +1m20.362s 16. Matthieu Vaxiviere Lotus +1m22.067s 17. Beitske Visser AV Formula +1m29.307s Retirements: William Buller Arden 16 laps Will Stevens Strakka 10 laps Marco Sorensen Tech 1 9 laps Meindert van Buuren Pons Racing 7 laps
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