The 23-year-old could barely contain her joy after finishing within a second of Italian winner Federica Brignone on the challenging slopes of Saalbach.
"It's amazing, my first world champs medal, it's so special… I just really wanted to go for it today, I just tried to treat today like any other race and I am really happy to have executed," Robinson said.
New Zealand's previous best world championships results were fourth placings - to Robinson at the 2021 giant slalom in Italy and slalom skier Claudia Riegler in 1996 in Spain.
Robinson was among the favourites to claim a medal, coming off victory at the most recent World Cup giant slalom race in Italy, which propelled her to the top of the World Cup series standings.
She said conditions didn't suit her style, with clear warm, conditions creating spring-like snow conditions.
"I was a bit worried today because these conditions, I usually struggle with the spring snow a bit, so I am really proud of myself."
Robinson was second after her first run, quickly finding her rhythm down a physically demanding course, 0.67 seconds behind Brignone.
The second-last skier to complete the second run, she opened up a 1.72sec lead over the rest of the field, with just Brignone to race.
The Italian responded brilliantly to win Italy's first gold in the event for 28 years, finishing with a final combined time of 2min 22.71sec, eclipising Robinson's 2:23.61.
"In the second run I just tried to go for it and not think too much, and honestly, it didn't feel good," Robinson said.
"It was rough and I think I was pushing it so much that I felt a bit out of control so I didn't know if it was fast or not. When I saw the green light I thought maybe it was good enough for gold but Federica was amazing today."
Brignone added gold to her silver in the super-G earlier in the championships.
It was a sweet moment for the 34-year-old after finishing second at last year's event and also bagging silver at the 2022 Olympics.
"Gold in the giant slalom is something I dreamed of throughout my career, I managed to stay calm after the first run, I knew I had a good lead," Brignone said.
"At the world championships we know it's all or nothing, I had the opportunity to go full throttle, today I was fine, I was focused on skiing.
"So much so that in the second run for a moment I was falling asleep and I said to myself 'move'. I'm out of breath but I was fine, I arrived at this event relaxed and at my best. I have to enjoy it as soon as it sinks in."
Reigning champion Mikaela Shiffrin didn't compete, the American great announcing on Tuesday that she was not mentally ready, having returned to racing in January two months after a crash the left her with a puncture wound in her abdomen.
