Darren Purse opened the scoring after 62 minutes but the turning point occurred when Bolton's Ricardo Gardner was sent off for a second booking.
Although Jay-Jay Okocha equalised Birmingham settled the game with further goals from Robbie Savage and substitute Geoff Horsfield.
It was a vital game for both teams and this was reflected in the early nervous play.
Birmingham mounted most of the attacks, but they were nearly caught out by a long ballfrom Ivan Campo which found Youri Djorkaeff, but he was robbed by Purse just as he wasabout to shoot.
Further indication of how fraught the game developed occurred when Bernard Mendycollected the first yellow card for a foul on Stan Lazaridis.
Only a desperate save by Jussi Jaaskelainen prevented Lazaridis from putting Birminghamahead at the start of a hectic attacking spell on the Bolton goal.
The second half moved up a gear when Purse opened his account in the 61st minuteafter a Robbie Savage corner was knocked on by Paul Devlin.
Purse powered in a low drive through a packed defence to lift Birmingham.
Bolton suffered their first major set-back when Gardner was sent off for a second yellowcard.
Okocha gave Bolton hope of a point when he scored a fine goal with a low cross-shotfollowing a left-wing cross from Mike Whitlow in the 72nd minute.
But Birmingham hit back in the next minute when Savage broke clear to roundJaaskelainen before slotting the ball into the net.
Substitute Dean Holdsworth lifted Bolton but they could not get back a second time andseven minutes from time Clinton Morrison's shot was pushed on to the post byJaaskelainen and Horsfield tapped home the rebound for an easy goal