The MP Motorsport driver lined up second before taking the lead at Turn 1 from polesitter Kush Maini (Campos).
He managed to build a solid lead from second-placed Iwasa (DAMS) and despite a virtual safety car and the Japanese driver beginning to close in, cleared off into the distance to cross the line 4.2s clear.
Iwasa, who had lined up fifth, had a fantastic start, jumping up to second by Turn 2, before setting about chasing his fellow Red Bull junior.
For five laps in the closing stages he put in faster laps than Hauger, but eventually proved no match for the Norwegian and settled for second.
Oliver Bearman snatched third from Theo Pourchaire for his fourth podium of the season, catching the ART title contender sleeping at Turn 1 to help Prema team-mate Frederik Vesti cling onto his championship lead by one point.
Hauger took the lead from Maini at Turn 1 as the Indian driver locked up, with Iwasa swooping into second around the outside of Turn 2.
Bearman, meanwhile, had a strong start from fourth and also made it past Maini to run third by lap two.
Maini took back third the following lap at Turn 1, braking late to pass his fellow rookie as Pourchaire closed on the pair.
Hauger was 1.7s clear of Iwasa by lap four, a gap which shrunk to 1.3s by lap 12 when the virtual safety car was deployed after contact between Clement Novalak (Trident) and Campos driver Ralph Boschung.
The Frenchman attempted a move up the inside of Turn 1 but made contact with the Swiss driver, with Boschung running into the barriers, while Arthur Leclerc (DAMS) was also caught up in the tangle but continued running.
Racing resumed on lap 13, with Pourchaire getting the jump on Bearman to snatch fourth up the inside of Turn 2.
Hauger was 2.5s clear on lap 18 when Iwasa was told he could push and managed to slash the gap to just one second by lap 24, putting in strong lap times to close on Hauger.
Pourchaire passed Maini at Turn 1 to take third with brief contact from behind from the Campos driver, though both escaped unscathed.
Bearman then squeezed through at Turn 2 for fourth, demoting Maini to fifth in just two corners.
But Bearman made it past Pourchaire with two laps remaining, catching the third-year driver sleeping to steal the final podium spot.
Jehan Daruvala, who lined up third for MP Motorsport but struggled with his start, finished fifth, having passed Maini at Turn 2 on the final lap.
Victor Martins finished seventh for ART, with Isack Hadjar rounding off the points-paying positions for Hitech.
Though Vesti missed out on the points, Bearman passing Pourchaire salvaged his lead, which is one point heading into Sunday's race.
