The Frenchman, who started in seventh for ART Grand Prix, had a great start and made it past a startline crash from Prema's Dennis Hauger and Jack Doohan (Virtuosi) to claim fifth by the first corner.
After pitting for medium tyres, he passed Campos Racing's Ralph Boschung for net second place on lap 19, before Nissany crashed out two laps later, handing Pourchaire the lead, which he held onto until the chequered flag.
Having started in 15th, Enzo Fittipaldi kept his nose clean amid a much interrupted race before claiming net second place from Boschung just four laps from the end to take his maiden series podium for Charouz Racing System.
Poleman Juri Vips suffered a poor start in his Hitech-run car, sliding down the order, before Hauger and Doohan's collision off the line prompted the first safety car and forced both rookies' retirements.
A great start from Nissany, who lined up sixth, put him into the lead, with Boschung in second and DAMS' Ayumu Iwasa in third heading into the first tour.
The top four pitted under the first safety car period, leaving Prema's Jehan Daruvala out front on the alternate strategy, having started on the medium compound.
While the Indian driver held the actual lead, Nissany ran out front of those who had already pitted, but crashed out at the final corner, ending his chance to take a maiden series victory and prompting a virtual safety car.
Daruvala pitted on lap 26, emerging into 14th, while second-placed Armstrong followed suit the next lap but suffered a poor pitstop, with a rear right problem leaving his wheels spinning on the jack.
With five laps remaining, Felipe Drugovich led for MP Motorsport from Marino Sato (Virtuosi) and Campos' Ollie Caldwell, with none of the three having pitted, and Pourchaire with the net lead in fourth place.
Logan Sargeant had been running in net third for Carlin, passing Boschung for second place on lap 31, but a mistake at Variante Alta dropped him behind the Campos driver and a charging Fittipaldi. The Williams junior eventually finished in seventh.
Seconds later, the Charouz driver took his chance to pass Boschung around the outside of Tamburello to claim his first series podium, leaving Boschung in third as Sargeant dropped down the order.
A crash from Carlin's Liam Lawson out of Acque Minerali prompted the final safety car period on lap 32, with the field following the Aston Martin until the chequered flag.
Clement Novalak took fourth place for MP Motorsport, with Iwasa in fifth and Frederik Vesti in sixth for ART Grand Prix.
| Cla | Driver | Team | Gap |
|---|---|---|---|
| 1 |
 Theo Pourchaire | ART Grand Prix | |
| 2 |
 Enzo Fittipaldi |  Charouz Racing System | 0.300 |
| 3 |
 Ralph Boschung |  Campos Racing | 0.700 |
| 4 |
Clement Novalak |  MP Motorsport | 1.400 |
| 5 | Ayumu Iwasa | DAMS | 1.800 |
| 6 |
 Frederik Vesti | ART Grand Prix | 2.100 |
| 7 |
 Logan Sargeant |  Carlin | 2.500 |
| 8 |
 David Beckmann | Charouz Racing System | 3.200 |
| 9 |
 Jehan Daruvala |  Prema Powerteam | 4.100 |
| 10 |
Felipe Drugovich | MP Motorsport | 4.300 |
| 11 |
 Marino Sato | Virtuosi Racing | 4.800 |
| 12 |
Jake Hughes | Van Amersfoort Racing | 5.000 |
| 13 |
 Marcus Armstrong | HitechGP | 6.200 |
| 14 |
Olli Caldwell | Campos Racing | 6.700 |
| 15 |
Richard Verschoor | Trident | 7.200 |
| 16 |
 Calan Williams | Trident | 7.700 |
| 17 | Amaury Cordeel | Van Amersfoort Racing | 1'21.400 |
|
Liam Lawson | Carlin | ||
 Roy Nissany | DAMS | ||
 Jüri Vips | HitechGP | ||
|
Jack Doohan | Virtuosi Racing | ||
 Dennis Hauger | Prema Powerteam | ||
| View full results | |||
