Blues put in a sparkling performance to end the regular npower Championship season with a 2-0 win against title winners Reading.
That result, combined with others elsewhere, means that Blues have finished fourth and will face fifth-placed Blackpool in the play-off semi-finals.
Substitute Adam Rooney set his side on their way with a well-taken finish mid-way through the first half, before Wade Elliott sealed the victory with a second-half penalty conversion.
Chris Hughton made four changes to his side with Nathan Redmond, Andros Townsend, Nikola Zigic and Guirane N'Daw all returning to the starting line-up.
Marlon King, Chris Burke and Erik Huseklepp were named on the substitutes' bench, but there was no place in the matchday squad for Jordon Mutch who was carrying a slight knock.
More than 4,000 Reading fans had travelled up for the game with many of them bringing inflatables and helping create a party atmosphere.
Both sides were evenly matched in the opening stages with neither really threatening too much offensively.
On the ten-minute mark there was the worrying sight of Nikola Zigic curled up in agony following a challenge, but the Serbian striker was able to carry on after prolonged treatment.
Curtis Davies came close to breaking the deadlock just after the quarter-hour mark when he met Andros Townsend's free-kick with a firm header, but unfortunately it went straight into Adam Federici's hands.
With just 19 minutes played, Blues were forced into a change when Zigic limped off after failing to recover from the injury he had picked up minutes earlier. Adam Rooney was sent on his place.
Blues were given a scare when Simon Church showed good technique to meet the ball with a volley in Colin Doyle's box, but he was unable to keep his effort down and it flew over the bar.
Within five minutes of entering the action Rooney made an impact as he fired his side into the lead.
The goal came on the break. Morgaro Gomis sent the ball long from his own half where it reached Redmond some 40 yards out. Redmond drove forward and just as he was closed down he threaded the ball sideways to Rooney. The Irishman made no mistake as he neatly sidefooted the ball past a diving Federici.
Blues came agonisingly close to doubling their advantage on the half-hour mark when Redmond fizzed a powerful 25-yeard effort inches over the bar. Then Wade Elliott tested Federici with a stinging effort, which the Royals' keeper managed to collect at the second attempt.
Blues were given a major scare after a mix-up between Doyle and David Murphy saw the ball heading towards their own net, but fortunately Ibanez was able to get to it and scoop it away from the danger zone.
With half-time approaching Adam Le Fondre managed to spring the Blues offside trap, but with just Doyle to beat he tried to dink the ball over the Blues keeper. But Doyle did well and managed to get something on the shot, which took the sting off it, and Ibanez was once again in the right place to clear the ball off the line.
Deep into stoppage time at the end of half Blues were awarded a free-kick in a dangerous position just to the right of the Reading box after Andros Townsend was chopped down. Wade Elliott curled it in and Ibanez met it with a glancing header but it flew back off the post and away.
Blues started the second period brightly and Elliott volleyed a great chance just over the bar with 50 minutes played. Blues had a major shout for a penalty when Townsend was brought down by Matthew Connolly, but Referee Robert Madley adjudged it to be just outside the box.
The subsequent dead ball from Elliott was blocked by the Reading wall. Curtis Davies put in a fine challenge to deny Simon Church a goal, but then seconds later Blues conceded a needless penalty. Ibanez climbed all over Alex Pearce to get to the ball and was penalised for his challenge.
But once again Doyle, the Blues hero, made a wonderful save to deny Ian Harte's 65th minute spot-kick. Hughton made his second substitution on 70 minutes when Chris Burke was sent on for N'Daw.
St. Andrew's erupted on 74 minutes when Referee Madley pointed to the spot for a second time, but on this occasion it was in Blues' favour after Jay Tabb had blocked Townsend's cross with his hand.
Elliott stepped up and made no mistake as he thumped the ball home to make it 2-0 to Blues. Rooney then came close to scoring his second and his side's third, but his glancing header went just the wrong side of the Federici's upright.
As the game entered stoppage time, Blues were awarded a second penalty, which was again taken by Elliott. But this time the midfielder saw his effort excellently saved by Federici.
But it was of little concern as Blues held on and now travel to Bloomfield Road to take on Blackpool next Friday night.
Blues: Colin Doyle, Peter Ramage, Curtis Davies (c), Pablo Ibanez, David Murphy, Wade Elliott, Morgaro Gomis, Guirane N'Daw (Chris Burke, 75), Andros Townsend, Nathan Redmond; Zigic (Adam Rooney, 19).
Subs not used: Jack Butland, Chris Burke, Erik Huseklepp, Adam Rooney, Marlon King.
Bookings: Murphy (37)
Goal: Rooney (24), Elliott (74).
Reading: Adam Federici, Matthew Connolly (Shaun Cummings, 62), Alex Pearce, Jay Tabb, Mikel Leigertwood (Bryn Gunnarsson, 71), Adam Le Fondre, Jobi McAnuff, Kaspars Gorkss, Simon Church, Hal Robson-Kanuu, Ian Harte.
Subs not used: Alex McCarthy, Noel Hunt, Joseph Hunt.
Bookings: Matthew Connolly (55).
Referee: Robert Madley.
Attendance: 25,516 (4,134 away fans)