The Briton set record-breaking pace in what proved to be a two-lap final run in qualifying.
Both McLarens went early in Q3, Norris the faster on the first of those flying laps before an insurmountable improvement on the second lap with a 1m09.954s.
That moved him ahead of practice pacesetter Charles Leclerc whose best was a 1m10.063s.
“It’s been a long time coming,” said Norris of his first pole since the season-opening Australian GP.
“I feel good. I don’t think you realise how good this feels, for quite a few struggles over the last couple months.
“Especially here in Monaco; It is a beautiful place, the hardest track to do it, up against the hometown hero, you know. I’m very proud of the whole team.
Oscar Piastri improved on his last run but was left third on the grid with a 1m10.129s.
Lewis Hamilton, who crashed at the end of Free Practice 3, ended up fourth fastest to cap off an improved showing from Ferrari.
Title contender Max Verstappen was just fifth fastest in Q3 ahead of Isack Hadjar and Fernando Alonso.
Esteban Ocon was eighth fastest while Liam Lawson made it two RBs in Q3 with ninth on the grid ahead of Alex Albon.
Main Red Bull Racing driver Yuki Tsunoda was bundled out of Q2 and will start from 12th behind Carlos Sainz.
The session was a disaster for Mercedes, with Kimi Antonelli technically making it through to Q2 – but only after hitting the wall at the Nouvelle chicane to end Q1.
He never got on track again, only for George Russell to tumble out of Q2 after rolling to a stop in the tunnel in the second segment.
The starts at 3pm local time tomorrow (11pm AEST).
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