Norris had already been rapid with a third-fastest time in Q1 and second place in Q2 and looked set to record his best ever qualifying result in a tightly contested Q3 shootout.
The Briton set a time which would have been good for third on the grid, behind polesitter Lewis Hamilton while splitting the Red Bulls of Sergio Perez and Max Verstappen, but saw his fastest laptime deleted due exceeding the track limits at Imola's Turn 9.
Instead, Norris ended up seventh on the grid, behind teammate Daniel Ricciardo, courtesy of his second-best laptime which was four tenths off the frontrunners. Even though his track limits violation appeared extremely marginal Norris took the full blame for losing his best time, admitting he "effed it all up".
"Yeah, pretty disappointed, pretty annoyed with myself," Norris told Sky Sports F1. "I think it was a very good day until then, the team did an awesome job. You know, the car really came alive in qualifying.
"We made a lot of improvements on Friday, but that one lap that I don't need to make a mistake on I effed it all up. It's the same for everyone, so at the end of the day it's my mistake."
Despite being relegated from third to seventh on the grid, Norris said he was happy with the rapid pace McLaren showed at Imola despite a slow start to the weekend in Friday practice.
"Yeah, I'm really happy," Norris replied when asked about his McLaren's potential. "Not with my job I've done but with the team.
"I think we didn't start the weekend off well at all. We really struggled in the beginning, but we made a lot of improvements. And I think we kind of understood a little bit more how the car works and how it comes alive, and a better operating window.
"That's one of the things we had to learn from Bahrain, where we struggled. We changed it this weekend and we've done a better job, just I didn't."