Norris secured his first victory in F1 around the Hard Rock Stadium, making use of an opportune pitstop under safety car conditions to leap ahead of Max Verstappen.
But once the neutralisation was lifted, the McLaren stretched clear to win unchallenged, albeit with Red Bull later revealing Verstappen had sustained floor damage in an earlier off-track excursion.
Yet the pace either side of the safety car for Norris suggested that an upgrade package for the British driver had paid dividends as McLaren aims to bridge the gap to Red Bull.
The Woking-based outfit only gave Norris the full upgrade package at Miami, with Piastri taking on a select number of new components.
But the Australian's performance was still strong and, having run as high as second in the first stint, had looked likely to fight for a podium position, only for a frustrated Carlos Sainz to lose the back end of his Ferrari at Turn 17 and swipe Piastri's front wing.
The contact forced Piastri to pit and eventually finish out of the points, but finding positives from the event, he said: "I think for both of us the car was really strong.
"For Lando to win the race on pace and to pull away from Max after the safety car, I think that's a very, very encouraging sign.
"So, very happy for him and for the whole team. I think we deserve it. Our trajectory in the last 12 months has been towards this moment."
Asked whether his team-mate's triumph with the full update package was a positive sign for himself moving forward, Piastri replied: "Yeah, definitely encouraging from that side and even with the car that I had, I think we were very strong as well."
Despite the optimism, Piastri has insisted McLaren still has work to do to understand some of the characteristics of the car.
"In these conditions on this track, the pace we had was unexpected," he conceded. "We don't fully understand why. We're a bit up and down on different days. But the fact that we can win a race on pace is a very very encouraging sign for the rest of the year.
