Piastri fell just short of challenging Russell and Lewis Hamilton in the closing laps in Spa-Francorchamps after a storming final stint.
Having started fifth, the Australian gained a place on the opening lap after his McLaren team-mate Lando Norris ran wide exiting La Source.
He then chased down Charles Leclerc following his second stop to set up a chance at claiming a second career win, falling short by just six tenths of a second.
It was a combative drive, his pass on the Ferrari a highlight as he went around the outside of the Monaco Grand Prix winner at Les Combes, prompting him to suggest it was won of his best in F1.
“I’m not sure my front jackman agrees,” he joked, after running long in the pit box at his second stop.
“I think it was a really strong race.
“To try and get past Charles was not easy, and I think if I didn’t manage to do it on that lap, I probably would have been stuck there for a long time.
“That was a pretty pivotal moment of the race. I think just the pace was very strong. I felt very, very good this weekend.
“Even on Friday, the pace was really strong. I’m just kicking myself a little bit that I didn’t get qualifying right.
“But yeah, I think it was a very strong weekend and probably one of my better races.”
Following his opening stop, Piastri ran fourth behind Leclerc, Hamilton, and the off-sequence Carlos Sainz.
The 23-year-old remained patient, biding his time around two seconds back from the cars ahead.
Having managed his tyres well through the middle of the race, when Leclerc pitted for a second time on Lap 25, and Hamilton a lap later, Piastri increased his pace, setting the fastest lap to that point.
While he rejoined behind the pair when he finally stopped on Lap 30, his efforts mean he’d largely covered off the undercut and given himself a tyre advantage for the run to the flag.
Using that in the closing stages, he reeled and passed Leclerc before pursuing the two Mercedes ahead – running out of laps just as he got to Hamilton’s gearbox.
“I think it was a really well-executed race,” Piastri reflected.
“I think the one-stop was a possibility and I think probably there’s a lot of people out there kicking themselves, they didn’t consider it more.
“We executed a great race. Had a quick car and ultimately just didn’t put it in the right position in qualifying yesterday.
“So I think given where we started, very happy. But yeah, ultimately I think there was a bit more potential this weekend.”
Employing a one-stop strategy, Russell gained track position that he was then able to maintain in the closing stages.
Starting on medium tyres, Russell took service on Lap 10, a lap before Piastri’s first stop.
Both swapped onto the hard compound tyre, the Mercedes driver carrying his set to the end.
It’s a strategy Piastri and McLaren considered but dismissed, leaving the Hungarian GP winner to suggest a bigger impact was the dirty air effect – even running well off the back of the car ahead.
“It did cross my mind, but not seriously enough,” Piastri said of switching to a one-stop strategy.
“I was amazed at how much difference the dirty air made today.
“When Lewis and Charles pitted for the second stop, I think I went one second faster just because I had clean air.
“So that was impressive, but then it felt like it kind of degged a little bit again after that point.
“With 16 laps, I think it was, or 15 laps around Spa, it felt like a pretty big risk to try and go to the end,” he added.
“I knew that even with the tyre advantage that we were building up, that we had a strong chance to try and win the race.
“Maybe we should have considered the one-stop a little bit more but I think with the two-stop, we did a good job of capitalising on it.”
By finishing second, Piastri added another 18 points to his championship tally to now sit fourth.
Norris added 10 by dint of finishing fifth, helping McLaren close the constructors’ championship deficit to Red Bull Racing to just 42 points.
There are now just 32 points between the McLaren pair in the drivers’ standings with 10 rounds remaining.