With Darren Huckerby playing his first league game since completing his permanent move to Norwich, the home fans must have expected to see their team make it five league wins in succession.
But the high-flying Canaries were brought down to earth by the lowly, but well organised, Bantams who scored the only goal of the game through on-loan Ipswich striker Alun Armstrong.
The home side kicked off but created few chances in the opening 20 minutes.
Andy Gray tested Robert Green with a 20-yard effort and Huckerby hit a fierce angled drive that Alan Combe beat away with no Canaries player on hand to take advantage of the rebound.
In the 25th minute David Wetherall headed off his goal line to deny Leon McKenzie.
On the stroke of half time Simon Francis crossed from the right and Armstrong beat Green at the far post with a crisp right-foot volley from eight yards.
At the start of the second half the home side battled to find a way through the visitors' solid defence, but lacked the cutting edge needed to find an equaliser.
The closest Norwich came to scoring was a header from Malky Mackay which went inches over the cross bar and a shot from Leon McKenzie that was on target but lacked power.
This was the first time this season that the Canaries had failed to score at home and it cost them dear as their lead at the top of the table was cut to just 2 points.
It was the Bantams' first away win under Bryan Robson, but he was quick to say: "It was a good performance but we must not get carried away."