Alonso dropped out of Q2 on Saturday at Zandvoort after being hampered by traffic, but managed to work his way up the order during the early part of the race.
Alpine was one of the first teams to switch to hard compound tyres, helping Alonso move up the order before planning a return to soft for the final stage.
The Spaniard managed to hold off McLaren’s Lando Norris after the last safety car to cross the line in seventh, moving up to sixth after Carlos Sainz’s five-second penalty was applied.
“It was good, today was 70 laps of qualifying because we couldn’t relax at any point,” Alonso explained after the race.
“The start was good but I lost places on the outside of Turn 1 so I had to fight really hard to get some back, then we put on the hard and had to push really hard to get that intermediate stint to work.
“And then when we thought it was a more relaxed part of the race at the end with good tire freshness, the safety car came and we have to fight again for the last 12 laps.
“It was a very demanding race, for sure.”
Lando Norris, McLaren MCL36, Fernando Alonso, Alpine A522
Photo by: Mark Sutton/Motorsport Images
Alonso managed to close in on Red Bull’s Sainz and Sergio Perez at one point as they battled for position, but he was wary that would open the door to anyone chasing him.
“I knew Carlos had a five-second penalty so I didn’t want them to fight too hard and get me in trouble with the car behind,” said Alonso.
“It was a good race and obviously I know the position gained at the end, we did it at Spa, one place for Ferrari and another here also for Ferrari. That way we always gain a position!”
Alonso revealed that Alpine’s pre-race simulations only saw him finish ninth, making the result a welcome boost for the team in its constructors’ battle with McLaren.
Alpine is now 24 points clear in the battle to top the midfield and finish fourth in the standings, helped by Esteban Ocon’s run to ninth.
But the Frenchman lamented running too long on the soft tire in the first stint, sitting out six more laps than Alonso, who managed to make it through the cut.
“We lost a good eight or nine seconds early on trying to keep that soft tire on longer,” Ocon said.
“That’s where we lost the race today. So it’s a little embarrassing, but it’s still a good recovery, getting both cars back to the points where we were. It’s a solid effort, but there was a lot more possible on the table today.
“Sixth was definitely my place today. That is what we are going to try to pursue in Monza.”