It was a point Birmingham deserved after taking a long time to get into the game which had earlier been dictated by Sunderland following a brilliant goal from Carlos Edwards.
Sunderland manager Roy Keane, however, has instilled his own personality on his side with such dramatic effect that the north-east club are rapidly emerging as the dark horses for promotion.
Edwards, who created such a favourable impression for Trinidad and Tobago in the World Cup, emerged as their match star with a crucial solo first-half goal.
A pacy player full of confidence he destroyed Birmingham with his speed, ball control and accurate finishing - ingredients which were sadly lacking in the Birmingham side until Campbell's introduction.
Birmingham, with seven points from their previous three games, wasted a glorious opportunity to go top on goal difference.
Meanwhile, Sunderland's big following chanted: "We're going to win the league but no-one believes us."
After this latest performance a lot of people need to sit up and take notice because the Black Cats are racing through on the rails and appear to have found the best going for their late title bid.
Sunderland are embarking on a spell when they are going to have an important bearing on the outcome of the Championship.
They are shortly to play both West Bromwich Albion and Derby County which could put them very much in the driving seat.
Their revival has been dramatic under Keane and with 19 points from their previous seven games they played with plenty of confidence and imagination.
It was particularly significant that Dwight Yorke, who made little or no impact in his short spell with Birmingham had a fresh vigour about his play and certainly contributed to Sunderland's attacking policy of taking the game to the opposition at every opportunity.
Some bright play very nearly gave Sunderland an early lead. Edwards and Tony Stokes were involved in a swift move which ended with David Connolly producing a snap-shot which Colin Doyle brilliantly saved.
The young Irishman certainly justified his inclusion as he read the game well but he had little chance in the 27th minute with the sparkling Edwards cut in from the right at full speed to unleash a rising drive into the far top corner of the net.
Speed was the essence of Sunderland's attacking play with Edwards and Connolly proving live-wires. The deft skill of Yorke was another feature that was prominent in a closely contested tussle.
Birmingham's suspect defence was certainly exposed as vulnerable as Edwards continued to enjoy a field day.
Sunderland were far from the side which was repeatedly turned over in recent seasons as they repeatedly put Birmingham on the rack with their confident play which got better the longer the game was in progress.
Their ability to break through Birmingham's midfield to attack the back four was of major concern for the Midlands club.
These problems at the back resulted in their front line being subdued with Nicklas Bendtner making little or no impact against the dominance of Nyron Nosworthy.
Only the assistant-referee's flag came to Birmingham's assistance early in the second half when Stern John's goal was ruled offside following a pass from Yorke.
Birmingham's reply was an attack down the left with Mat Sadler providing the cross to the onrushing Seb Larsson only for Sunderland's new goalkeeper Marton Fulop to save a certain equaliser with his legs.
Nosworthy, not for the first time, came to Sunderland's rescue with a goal-line clearance to keep out a Bendtner effort after sparkling work by Seb Larsson.
Birmingham sent on strikers Rowan Vine and Campbell and these two combined in a hectic finish to produce the equaliser four minutes from time.
Vine's low cross was turned in at close range by Campbell who celebrated his seventh league goal of the season with a dive towards the corner flag!