Team-mate Tiago Monteiro followed him home in second, while Norbert Michelisz ensured a podium lockout for the Japanese marque as he held off Yvan Muller to finish third.
Tarquini converted pole position into an early lead and gradually eased away from the field, his cause helped by the fact Monteiro, Michelisz and Muller spent much of the race within one second of each other.
At the halfway mark Muller fired off the quickest first sector of the race, but a charge never materialised and he faded over the final laps.
Freed of Muller's attentions Michelisz closed in on Monteiro but never truly mounted a challenge to pass, the pair finishing just 0.4s apart over the line.
Tom Coronel finished best of the rest in fifth after passing James Nash's Bamboo Chevrolet two laps from the finish when the Briton ran deep into Turn 8.
The pair had been covered by less than half a second for much of the race until Coronel's late pass.
Nash, who ended up sixth, had jumped team-mate Alex MacDowall away from the start, and also gained ground when Tom Chilton and Freddy Barth made contact early on.
That dropped Chilton down to seventh, but he was to suffer worse as he lost went off into the Turn 6 gravel in a race-ending incident on only the second lap.
Seventh went to Michel Nykjaer's NIKA Chevrolet, with MacDowall a close eighth and Pepe Oriola a relatively lonely ninth.
Barth went on to claim 11th, beating fellow BMW driver Stefano D'Aste to the honour by just five thousandths of a second.
The pair had been part of a four-way scrap for the final points-paying positions, with Proteam BMW's Mehdi Bennani and Lada's James Thompson also involved.
Bennani prevailed by claiming 10th, while Thompson - who had swapped positions with Barth twice on the penultimate lap - 13th.
Results - 10 laps: Pos Driver Team/Car Time/Gap 1. Gabriele Tarquini Honda 22m18.761s 2. Tiago Monteiro Honda + 1.202s 3. Norbert Michelisz Zengo Honda + 1.616s 4. Yvan Muller RML Chevrolet + 5.091s 5. Tom Coronel ROAL BMW + 5.975s 6. James Nash Bamboo Chevrolet + 7.748s 7. Michel Nykjaer Nika Chevrolet + 9.760s 8. Alex MacDowall Bamboo Chevrolet + 10.078s 9. Pepe Oriola Tuenti SEAT + 14.055s 10. Mehdi Bennani Proteam BMW + 19.374s 11. Fredy Barth Wiechers BMW + 21.474s 12. Stefano D'Aste PB BMW + 21.479s 13. James Thompson Lada + 21.837s 14. Darryl O'Young ROAL BMW + 24.891s 15. Fernando Monje Campos SEAT + 25.937s 16. Marc Basseng Munnich SEAT + 27.197s 17. Robert Huff Munnich SEAT + 27.507s 18. Charles Ng Engstler BMW + 36.500s 19. Franz Engstler Engstler BMW + 41.278s 20. M.Kozlovskiy Lada + 1 lap 21. Rene Munnich Munnich SEAT + 2 laps Retirements: Tom Boardman Special Tuning SEAT 6 laps Tom Chilton RML Chevrolet 1 lap
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