The Hitech driver started on pole, getting a good start before taking a commanding lead in Saturday’s sprint race.
Pourchaire kept the leader in his sights for the whole race, never dropping more than 2s behind, but Armstrong kept consistent pace to take the win.
He had built a 1.2s lead by lap six, holding off the ART driver through a virtual safety car before extending the gap out front to almost 2s by lap 19.
Armstrong crossed the line a second ahead of the Frenchman, who faces a post-race investigation for exceeding track limits.
Pourchaire faced a battle of his own, with Jack Doohan taking third place at Turn 3 on the first lap before setting his sights on second.
Pourchaire was able to hold off the charging Australian, building the gap to 1.2s, but the Virtuosi driver clawed back time and was just 0.7s behind by the chequered flag.
Carlin’s Liam Lawson stalled on the grid at the start of the formation lap, forcing him to start the race from the pitlane.
With Armstrong streaking off from the startline, Doohan closed on Richard Verschoor (Trident), taking the position at Turn 3 before championship leader Felipe Drugovich followed him through.
Further back, Frederik Vesti moved up to ninth, with Logan Sargeant taking seventh from Amaury Cordeel.
Verschoor, Vips, Sargeant and Ayumu Iwasa were embroiled in an intense battle for fifth by lap six, with the Hitech man emerging in front to take the place, having started ninth.
Drugovich remained in Doohan’s DRS zone by lap eight, but a virtual safety car prompted by Lawson stopping at Turn 3 on lap 12 neutralised the field, the Carlin driver crawling back to the pits to retire.
Pourchaire was shown the black and white flag for track limits on lap 15 while running 1.4s behind the leader, while Doohan had built up 1.9s to Drugovich.
By lap 19, the gap from Armstrong to Pourchaire was almost 2s, with 1.3s from him to Doohan and another 3s to Drugovich in fourth.
Four laps later, Doohan was just 0.5s behind the Frenchman, holding his position to the line.
A late retirement came from Campos Racing sub Roberto Merhi, who replaces Ralph Boschung this weekend while he suffers from neck pain.
Vips finished in fifth, with Verschoor and Sargeant in sixth and seventh. Iwasa, who faces an investigation for forcing off Sargeant, took eighth, with Enzo Fittipaldi and Dennis Hauger rounding of the top ten.
Feature race polesitter Vesti was handed a five-second penalty for exceeding track limits after having been shown the black and white flag on lap nine. He would have finished ninth, but dropped to 12th with his penalty.
F2 Austria - Race 1 results:
| Cla | # | Driver | Team | Gap |
|---|---|---|---|---|
| 1 | 7 |  Marcus Armstrong |  HitechGP | |
| 2 | 10 |  Theo Pourchaire | ART Grand Prix | 1.000 |
| 3 | 3 |  Jack Doohan | UNI-Virtuosi | 2.100 |
| 4 | 11 |  Felipe Drugovich |  MP Motorsport | 5.000 |
| 5 | 8 |  Jüri Vips | HitechGP | 11.900 |
| 6 | 20 | Richard Verschoor |  Trident | 14.800 |
| 7 | 6 |  Logan Sargeant | Carlin | 15.200 |
| 8 | 17 |  Ayumu Iwasa | DAMS | 15.800 |
| 9 | 22 | Enzo Fittipaldi |  Charouz Racing System | 17.500 |
| 10 | 1 |  Dennis Hauger | Prema Powerteam | 19.300 |
| 11 | 2 |  Jehan Daruvala | Prema Powerteam | 21.600 |
| 12 | 9 |  Frederik Vesti | ART Grand Prix | 22.000 |
| 13 | 16 |  Roy Nissany | DAMS | 31.700 |
| 14 | 21 | Calan Williams | Trident | 34.500 |
| 15 | 12 | Clement Novalak | MP Motorsport | 38.600 |
| 16 | 25 |  Amaury Cordeel | Van Amersfoort Racing | 40.100 |
| 17 | 24 | Jake Hughes | Van Amersfoort Racing | 40.200 |
| 18 | 14 | Olli Caldwell |  Campos Racing | 53.500 |
| 19 | 15 | Roberto Merhi | Campos Racing | |
| 23 |  Cem Bolukbasi | Charouz Racing System | ||
| 5 | Liam Lawson | Carlin | ||
| 4 | Marino Sato | UNI-Virtuosi | ||
| View full results | ||||
