The Serbian netted a last-gasp point for Blues for the third time this season but his header owed more to a glaring error from Kuszczak, who allowed the ball to slip through his hands.
Steven Caldwell headed the hosts in front after 18 minutes with what was his first league goal in 18 months at the club from Rob Hall, but the Seagulls levelled soon after courtesy of Ashley Barnes' sixth of the season and second in as many games.
Andrea Orlandi broke down the left and cut a ball back for Barnes who fired into the bottom corner from 20 yards.
David Lopez volleyed home in style what looked to be the winner just before half-time only for Zigic to equalise late on, with Blues' sought-after goalkeeper Jack Butland then producing a wonder save to keep out Dean Hammond.
Brighton will certainly feel like it is two points dropped having looked set for their first win over Birmingham in eight attempts since 1989 and only their second ever success at St Andrew's.
And Albion's late setback has seen them drop five points beind the top six although they have moved up one place in the npower Championship table to eighth.
Cash-strapped Blues continue to look increasingly over their shoulder at the relegation places, with just win in their last 10 games. They remain in 20th spot - five points clear of danger.
- Sports & Recreation