Arsenal may not have won a trophy since 2005 there will be little sympathy from Birmingham on that score as they won only their second major title in their 136 year history.
Birmingham have now won 9 of their 10 cup games this season which contrasts sharply with their league form which sees them battling against relegation.
Perhaps this result will give them confidence to avoid the drop as they held their own against the favourites taking the lead just before the half-hour.
As the Blues score most of their goals from set pieces and the Gunners concede most, it was no surprise that following a corner Nikola Zigic headed-in from close range.
Keith Fahey hit a post for Birmingham but just as it seemed the game was going into extra time some awful defending handed the Carling Cup trophy to the Blues.
Zigic, who was a constant threat in the air, caused confusion in the Gunners ranks and keeper Wojciech Szczesny and defender Laurent Koscielny allowed Obafemi Martins a simple tap in.
Referee: Mike Dean
Venue: Wembley Stadium
Arsenal scorers: Van Persie 39
Birmingham scorers: Zigic 28, Martins 89
06 Koscielny (yellow card)
22 Clichy (yellow card)
17 A Song
23 Arshavin (Chamakh 77)
10 Van Persie (Bendtner 69)
07 Larsson (yellow card)
08 Gardner (Beausejour 50)
12 Ferguson (yellow card)
18 Fahey (Martins 83)
19 Zigic (Jerome 90+2 (yellow card)