The ART driver lined up fourth, making his way up to second behind Marcus Armstrong before the pitstops.
But a slow stop for the Hitech driver allowed Pourchaire out ahead, taking the net lead ahead of Enzo Fittipaldi before picking off those ahead who were yet to stop.
Despite the Charouz driver closing the gap on the leader to just 1.2s by the final laps, he was unable to make it past for his maiden victory.
Pourchaire's win, with Drugovich finishing in ninth, closes the title fight to just 21 points going into the summer break, with four rounds remaining.
Fittipaldi settled for second, holding off polesitter Ayumu Iwasa despite making a mistake at the chicane on the last lap to take his second podium of the weekend.
Armstrong took the lead from Iwasa off the line, with the top four all running on the soft compound tyre, before Pourchaire passed the Japanese driver for second by Turn 3.
Title contender Logan Sargeant had a poor start, dropping six places off the line.
Fittipaldi was up to fifth by lap four, having started ninth, passing Frederik Vesti up the inside of Turn 3, while the ART driver was handed a five-second penalty for forcing another driver off the track.
Armstrong had a 1.6s gap to Pourchaire by lap six, with Iwasa looking at second place but staying behind the Frenchman.
Drugovich was first to pit for medium tyres on lap seven, as did Jehan Daruvala (Prema), exiting into 19th place.
The move prompted the top three to pit the following lap with Pourchaire and Iwasa emerging in front of Armstrong to take the net top two, the New Zealander missing out courtesy of his location in the pitlane.
Pourchaire and Iwasa also emerged ahead of Drugovich, the former taking 16th on the road as his title rival fell back.
Drugovich passed Armstrong the following lap, with Fittipaldi pitting as Vesti took the lead on the road.
A quick stop for the Charouz man put him back out behind Pourchaire but ahead of Iwasa, despite him having asked to pit the lap before, and igniting a battle for net second.
Dennis Hauger pitted for the soft tyres on lap 19, the Prema driver having struggled on the medium tyres and forced into an earlier-than-ideal stop.
Pourchaire continued to move through those yet to stop, passing David Beckmann at Turn 1 for seventh place on the road, while Drugovich closed in on Iwasa.
Armstrong took net fourth from Drugovich on lap 23, the MP Motorsport driver struggling with the medium tyres.
Vesti pitted three laps later and served his five-second penalty, emerging eighth, while Juri Vips pitted behind him and came out 10th, with both struggling to get temperature into their tyres and locking up.
Sargeant pitted on lap 27, rejoining in 17th, while Vips retook ninth from Daruvala up ahead as Vesti passed a yet-to-pit Amaury Cordeel (Van Amersfoort) for sixth two laps later.
Vesti was on the back of Drugovich in the closing laps, eventually passing him at Turn 14 on lap 31 as spots of rain began to fall around the circuit, before Vips did the same at Turn 2 the following lap.
Richard Verschoor was next to pass Drugovich, demoting the championship leader to ninth, while up ahead Vesti passed Armstrong just two laps from the end to take fourth.
Vips followed suit on the penultimate lap to secure fifth, with his teammate settling for sixth, as Lawson made it past Verschoor for seventh.
Jack Doohan, who started 10th, retired in the opening laps having suffered a mechanical issue.
| Cla | Driver | Team | Gap |
|---|---|---|---|
| 1 |  Theo Pourchaire | ART Grand Prix | |
| 2 |  Enzo Fittipaldi |  Charouz Racing System | 3.600 |
| 3 |  Ayumu Iwasa | DAMS | 5.900 |
| 4 |  Frederik Vesti | ART Grand Prix | 6.700 |
| 5 |  Jüri Vips |  HitechGP | 9.600 |
| 6 |  Marcus Armstrong | HitechGP | 13.500 |
| 7 | Liam Lawson | Carlin | 14.700 |
| 8 |  Richard Verschoor |  Trident | 20.100 |
| 9 | Felipe Drugovich | MP Motorsport | 28.600 |
| 10 |  Logan Sargeant | Carlin | 29.200 |
| 11 |  Jehan Daruvala | Prema Powerteam | 42.400 |
| 12 | Clement Novalak | MP Motorsport | 42.800 |
| 13 |  Cem Bolukbasi | Charouz Racing System | 45.700 |
| 14 |  David Beckmann | Van Amersfoort Racing | 47.400 |
| 15 | Marino Sato | UNI-Virtuosi | 47.600 |
| 16 |  Roy Nissany | DAMS | 48.300 |
| 17 |  Calan Williams | Trident | 51.200 |
| 18 |  Amaury Cordeel | Van Amersfoort Racing | 56.000 |
| 19 |  Dennis Hauger | Prema Powerteam | 1'17.900 |
| 20 | Olli Caldwell |  Campos Racing | |
| 21 | Roberto Merhi | Campos Racing | |
| 22 | Jack Doohan | UNI-Virtuosi | |
| View full results | |||
