The defeat was the Porcupine’s first at the Baba Yara sports stadium this season, bringing an end to a 10-game unbeaten home run.
The match was played under a cloud of anticipation after Kotoko’s head coach Karim Zito resigned earlier in the week, with Prince Yaw Owusu stepping in as interim boss alongside assistant Mohammed Hamza Obeng.
The coaching shake-up came amid a difficult league campaign for the Porcupine Warriors.
Hearts of Oak took the lead in the 14th minute through defender Baba Adamu, who rose highest to head home from a dangerous set-piece delivery, silencing the home crowd.
Although Hearts were reduced to 10 men midway through the first half after Emmanuel Amankwah received a second yellow card, they remained resilient.
The Phobians retreated into a compact defensive shape and stood firm against sustained Kotoko pressure.
Kotoko pressed for an equaliser throughout the second half but created only a handful of clear chances.
Their best efforts were kept out by an alert Hearts defence and goalkeeper Benjamin Asare, who earned man of the match honours for his commanding display.
Hearts of Oak head coach Didi Dramani acknowledged the importance of the win.
“It was just a league game, the plan was to win and keep the pressure on the Medeama,” he said.
Meanwhile, Kotoko interim coach Prince Owusu admitted the result will have a huge impact on their season.
“This defeat has made the season very tough for us. The season is not over, we will fight till the end.”
The victory is significant on several fronts. It hands Hearts a rare away win against Kotoko in Kumasi and also sees them close the gap with league leaders Medeama to just five points, keeping their title ambitions alive as the season enters its business end.
Kotoko, meanwhile, remain outside the top four and now face pressure to regroup quickly under interim leadership as they chase their own title hopes.
