The Owls strengthened their grip on their play-off place with a 3-0 win under the lights at Hillsborough.
Jordan Rhodes set the ball rolling early in the first half, with strikes from Sam Winnall and substitute Adam Reach sealing the hosts’ most comprehensive win of the season so far.
Blues will consider themselves as they hit the post once and the crossbar twice but Wednesday showed their clinical side to emerge triumphant.
Indeed it was all the Owls in the opening stages and they were rewarded nine minutes in, with Rhodes opening his S6 account.
After Winnall tested Blues keeper Tomasz Kuszczak almost from the kick off, the former Middlesbrough man went one better.
Ross Wallace drilled a corner into the danger zone where Rhodes was duly lurking to head home from close range.
It was the perfect start to the hitman’s Hillsborough career – but Birmingham stirred and made immediate inroads in a bid to restore parity.
And they came within a whisker of doing exactly that, twice in as many minutes.
First Sam Hutchinson inadvertently headed against his own post, then moments later Emilio Nsue thundered a fierce drive against the bar.
Winnall responded by bringing another fine save from Kuszczak and although the visitors certainly posed a threat, the Owls finished the first period in the ascendancy.
Wednesday began the second half in similar fashion and once again Winnall forced Kuszczak into action, this time with a snapshot on the angle.
Winnall then nodded a Wallace corner over the bar before the Blues broke and David Davis was just off target with a rising drive.
Craig Gardner went closer still with 12 minutes to go, executing a super effort from the edge of the area that clipped the top of the woodwork.
And that proved key as Wednesday doubled their lead from their very next attack. Jack Hunt sent the perfect delivery into the mix and Winnall was on hand to stoop and head past Kuszczak.
That took the wind from the Birmingham sails and took a final blow on 86 minutes when Reach broke free down the middle to calmly slot past Kusczcak.
Wednesday: Westwood, Hunt, Loovens, Sasso, Fox, Wallace (McManaman 85), Bannan (Abdi 81), Hutchinson, Forestieri (Reach 66), Winnall, Rhodes