Dean Windass' brace gave struggling Hull a comfortable victory at home to a Birmingham side handicapped by the dismissal of Radhi Jaidi.
Windass netted his first goals since returning to his home-town club
Ray Parlour was the instigator behind Hull's breakthrough when he crossed low for Windass who clinically swept home.
Birmingham's plight worsened when centre-back Jaidi was shown a straight red card for a professional foul.
Windass grabbed his second from the spot after Nicky Forster was chopped down in the box by Martin Taylor.
Windass' goals were his first since rejoining his hometown club from Bradford.
Birmingham offered little going forward and were reduced to 10 men when Stuart Elliott raced onto a long ball but was brought down by Jaidi, who was sent off by referee Colin Webster.
Their best chance of the first half fell to Gary McSheffrey who controlled a loose clearance 25 yards from goal and executed a superb left-footed volley but Bo Myhill tipped over for a corner.
Hull first-team coach Steve Parkin:
"The important thing was not only to bounce back but to put on a performance that we felt was acceptable to everyone at the club.
"They have done that with some aplomb. They were committed and determined.
"We were disappointing on Tuesday but we gave bad goals away and have worked tirelessly to get a clean sheet here."
Birmingham boss Steve Bruce:
"It was a very, very disappointing afternoon.
"We never really fully recovered from the sloppy start and I have no complaints with the sending-off.
"That was possibly our worst display away from home and everything seemed to conspire against us."
Hull: Myhill, Coles, Turner, Delaney, Ricketts, Parlour (Welsh 80), Ashbee, Livermore (Marney 89), Elliott, Forster, Windass (Parkin 90).
Subs Not Used: Duke, Doyle.
Goals: Windass 10, 57 pen.
Birmingham: Doyle, N'Gotty, Martin Taylor, Jaidi, Sadler, Clemence, Larsson (Bendtner 46), Danns, Campbell (Kelly 39), Jerome (Vine 65), McSheffrey.
Subs Not Used: Maik Taylor, Nafti.
Sent Off: Jaidi (34).
Ref: C Webster (Tyne & Wear).