The 4-2 win for the Cherries, which came courtesy of a Lewis Grabban brace, lifts them to 10th and only five points behind sixth-placed Reading.
For Birmingham, this loss extended their winless sequence at St Andrew's to 15 league games and left them just five points above the relegation zone.
They even trained at the ground in midweek in an attempt to end their home hoodoo but it was to no avail as Bournemouth sealed their fate with three goals in a 13-minute first-half spell to maintain their record of never having been beaten at Birmingham in seven visits.
The high-flying Cherries took full advantage of some very indifferent play to score in quick succession through Matt Ritchie and two from Grabban, including a gift-wrapped penalty.
Ian Harte exposed Birmingham's indifferent defensive work with the fourth goal after 52 minutes with a long-range, curling left footed shot into the roof of the net. It was only after this that Birmingham came to life and their inspiration was Federico Macheda.
The on-loan striker from Manchester United scored after 57 minutes and raised Birmingham's hopes of a comeback with a second strike in the 72nd minute.
Bournemouth, who have now won six of their last seven games, displayed a confident air in the early stages and their positive attacking play was rewarded with a 14th-minute goal from Ritchie.
Harte initiated the goal with an intelligent low cross from the left which was picked up by Grabban, and he quickly switched the ball out to the right where the lurking Ritchie was on hand to hammer a cross-shot past the helpless Darren Randolph.
The Birmingham goalkeeper was similarly placed when Bournemouth increased their lead.
Harry Arter set the Cherries on the goal path with an astute pass to Marc Pugh. His cross was agonisingly deflected by Chris Burke out of the reach of Randolph and Grabban was on hand to tap home a simple goal at the far post.
Randolph continued to have a nightmare of a game in the 27th minute when he needlessly brought down Grabban as the ball was running out of play well wide of his goal.
Grabban nonchalantly dispatched the resultant penalty for his 19th goal of the season to put the Cherries into an unassailable lead.
The nearest Birmingham came to reducing the arrears in the first half occurred a couple of minutes before the break when skipper Paul Robinson nodded a header goalwards only for Cherries number one Lee Camp to make a superb fingertip save.
Harte compounded Birmingham's embarrassment with a 52nd-minute strike from distance which arced into Randolph's net.
Substitute Macheda grabbed Birmingham's first goal after 57 minutes when he scored with a low left-footed shot following a headed pass from young Jordon Ibe.
Macheda notched his second with a 20-yard volley to ignite Birmingham but Bournemouth regrouped to hold on for their victory.