Joe Garner marked his debut for Town with the only goal of the game to get the season up and running with a win.
The former Preston striker, who bagged six goals in pre-season, maintained his run of form in front of goal with a clinical finish early in the second-half.
Freddie Sears went close to a second for Mick McCarthy’s side but Town’s injury woes continued with Andre Dozzell carried off before the break with suspected knee ligament damage.
Town gave a debut to Dominic Iorfa as well as Garner as the season got underway against a Birmingham side tipped to make a top six challenge under Harry Redknapp.
Dozzell, fresh from England U19 success last month, had the first shot of the new campaign, sending a left footer wide.
Birmingham went much closer soon after, Michael Morrison’s header needing an excellent save from Bart Bialkowski to keep it out.
Emilio Nsue tested Bialkowski from distance, then the impressive Iorfa forced a corner with a strong run, Garner denied from the flag kick.
Garner, a summer signing from Rangers, almost found Grant Ward with a deflected ball through in an even opening to the game, David Davis threatening for the visitors with a curler just over after a spell of pressure for Birmingham.
Iorfa then found Sears with a clever pass inside but Morrison was alert to the danger.
Davis couldn’t control his lob after getting on the end of a long ball down the Town left, Iorfa - who was finding space supporting from Town’s right, wayward with a cross from a good position.
Bialkowski was off his line smartly to deny Clayton Donaldson after slick passing by Redknapp’s side on the edge of the Town box, then a terrific pass from Dozzell set up Sears who saw his shot deflected behind.
On the stroke of half-time, Town lost Dozzell to what looked like a knee ligament injury, the teenager receiving lengthy treatment before he was stretchered off. Flynn Downes the replacement - his debut.
Jordan Spence had an anxious wait before receiving a yellow card after pulling back Donaldson when he looked in on goal, albeit a long way out but on 50 minutes, Blues were ahead - Garner converting from Jonas Knudsen’s cross.
Another cross from the Danish international tested David Stockdale in the Birmingham goal, the former Town loanee then getting in the way of a Sears cross as Blues enjoyed a spell of pressure on the visitors’ goal.
Craig Gardner volleyed wide from the edge of the box as Birmingham looked for a way back into the game, Luke Chambers doing well to head the ball back to Bialkowski under pressure from Donaldson, then Nsue saw a fierce cross put behind by Bialkowski’s strong hand.
Town made a second change with Adam Webster on for Iorfa and seconds later Blues could have extended the lead, Sears prodding the ball wide from close range after excellent work by Spence.
Bialkowski held firm from a header from Cheikh Ndoye, while Downes didn’t look out of place at all in his first appearance in the first-team, clearing the danger twice in quick succession as Blues kept Birmingham at bay to start the season in the best possible way.
Town: Bialkowski, Iorfa (Webster 73), Spence, Chambers, Smith, Knudsen, Skuse, Dozzell (Downes 45), Ward, Garner, Sears. Subs not used: Gerken, McGoldrick, Celina, Nydam, Kenlock. Booked: Spence.
Birmingham: Stockdale, Nsue, Grounds, Roberts, Morrison, Gardner, Ndoye, Davis, Maghoma (Keita 79), Donaldson. Subs not used: Kuszczak, Shotton, Kieftenbeld, Brock-Madsen, Harding, Gleeson. Booked: Roberts.
Att: 18,153