No fewer then seven of the Blues' Championship rivals were toppled by lower league opposition on Tuesday night, but there were few scares for Alex McLeish's side as they showed their class with a four-goal salvo to ease them through to the second round.
Peter Taylor's Wanderers went into the game boasting a decent record against higher division opponents in this competition - most notably in their run to the semi-finals in 2006 under former boss Paul Lambert.
But it didn't take long for the visitors' class to tell against a youthful and clearly nervous Wycombe side as Craig Woodman failed to deal with Gary McSheffrey's deep cross after 14 minutes.
Garry O'Connor seized onto the loose ball and his pull back to the edge of the box was fired home by Medhi Nafti.
O'Connor then went close to adding his name to the scoresheet when his header from Stuart Parnaby's cross skidded just wide.
With Nafti and skipper Lee Carsley dominating the midfield, Birmingham rarely had to find top gear and were almost gifted a lucky second when David Murphy's mis-hit cross forced home keeper Jamie Young into a decent tip over.
O'Connor went close again just after the break, but this time his powerful header was spectacularly beaten away by Young.
Wycombe briefly showed signs of life when Chris Zebroski firstly volleyed over from close range before then seeing his shot from Nathan Ashton's cross well saved by keeper Colin Doyle.
The game was over as a contest in the 64th minute though as Sebastian Larsson danced into the box before slotting the ball neatly into the bottom corner.
Substitute Cameron Jerome added a third with a looping header on 73 minutes and fellow sub Quincy Owusu-Abeyie put the gloss on the final scoreline with a neat curling shot four minutes from time.