The only goal of the game was scored by Norwich substitute Mario Vrancic after 87 minutes, just a minute after the visitors were controversially reduced to 10-men when Adam Clayton was sent off for a second yellow card.
Truth be told, Norwich had almost three quarters of the possession and limited Blues to less than a handful of chances, but it was still a cruel blow to concede so late on having stood firm for so long.
Aitor Karanka made three changes to the Blues side that were beaten by Sheffield Wednesday at the weekend.
Jonathan Leko started from the off, ahead of Jeremie Bela who dropped to the bench. Meanwhile, Ivan Sunjic and Marc Roberts came in for Gary Gardner and Ivan Sunjic. Last season's top scorer Lukas Jutkiewicz was still unavailable because of illness.
Norwich were the livelier side in the opening stages and Maxime Colin was forced to put the ball behind from close range under pressure.
Leko was soon showing glimpses of the pace and ball control that saw Blues add him to their ranks.
The visitors were almost made to pay for dallying on the ball after George Friend was caught in possession inside his own box, but luckily Hugill fired into the side netting for the Canaries.
But the Blues defender more than made up for his error minutes later with a fabulous tackle to block Aarons' attempt.
Etheridge was then forced to palm away a shot from Rupp from outside the box.
Blues were holding their shape reasonably well and making it difficult for the Canaries to play through them, although Cantwell came close as he fired wide from 10 yards.
The same Norwich player had an even better opportunity minutes later after Leko lost the ball outside his area, but this time Cantwell was denied by Etheridge who made himself big and saved.
With 43 played, Blues were inches away from taking the lead themselves after Leko laid the ball off to Ivan Sanchez, but the Spaniard curled his shot just inches over the bar, a deflection taking it behind for a corner.
Half-time: Norwich 0 Blues 0
Less than two minutes into the second-half Hugill found himself in space on the edge of the Blues box but he blasted the ball over the bar.
Pukki then tried his luck with a shot on the angle but it was comfortably saved by Etheridge at his near post.
With 55 minutes on the clock Karanka made his first substitution as he sent on Bela in place of Leko.
With just over an hour played Sanchez won the ball on the half-way line before running on with it. His pass found Bela, but his shot was saved by Krul.
At the other end of the pitch Cantwell put the ball in the back of the Blues net, but the goal was disallowed after he was flagged for being offside.
The lively Cantwell was then on the end of a neat piece of passing play by the hosts, but this time he volleyed the wrong side of the post.
Colin was forced to put his body on the line with a block to deny Cantwell who looked odds on to score at the far post.
The French defender then had to be alert to take the ball off Idah's foot, with the Norwich substitute poised to shoot from a really dangerous position.
With less than 15 minutes of normal time remaining Blues were regularly being forced back into their own third of the pitch and having to defend in numbers but standing up to the challenge.
Blues were relying on the counter-attack and saved comfortably from Bela.
On 86 minutes, Blues were reduced to 10 men after Clayton received a harsh second caution following a challenge on Cantwell.
And it proved to be a decisive moment, as just a minute later Hogan was caught in possession in midfield and Norwich broke with pace before Vrancic slammed the ball home to fire his side into a late lead.
Three minutes into stoppage time a cross from the right found Hogan just six yards out, but he was unable to get hold of the ball properly and the chance was gone.
And then in the final seconds Dean was unable to find Hogan with his cross from the right.
Norwich City (4-2-3-1): Krul; Aarons, Hanley (C), Gibson, Qunitilla; Rupp, Skipp (Vrancic, 80); Buendia, Pukki (Placheta,85), Cantwell; Hugill (Idah, 69).
Subs not used: McGovern (GK), Tettey, McLean, Martin.
Goals: Vrancic (87).
Blues (4-2-3-1): Etheridge; Collin, Dean (C), Friend, Pedersen; Roberts (San Jose, 90+1), Clayton; Sanchez, Sunjic, Leko (Bela, 55); Hogan.
Subs not used: Prieto (GK), Boyd-Munce, Dacres-Cogley, Gardner, McGree.
Bookings: Dean (54), Friend (88), Sunjic.
Sending off: Clayton (86 - Yellow cards 50, 86)
Referee: Oliver Langford.