Midfielder Michael Akuffo expertly converted a spot-kick on the 31st minute before Nathaniel Asamoah clinically finished off an Ahmed Toure pass from close range.
Youngster Michael Anaba then sealed the victory for the 'Porcupine Warriors' on the stroke of full time.
Kotoko needed the maximum points to revive their campaign.
Referee John Attikese awarded a penalty to Asante Kotoko on the half-hour mark after Ashanti Gold defender Michael Boakye hacked down midfielder Daniel Nii Adjei inside the box.
Midfielder Akuffo stepped up to expertly convert the kick and Kotoko were 1-0 up.
AshGold tried to forge a comeback but the stumbled again five minutes later as Ivorian striker Ahmed Toure run into space before setting up Nathaniel Asamoah to coolly finish off to make it 2-0.
The opportunities were scanty for AshGold but their strikers wasted the few opportunities chances that came their way.
Nathaniel Asamoah got close to hitting a brace on the 73rd minute after shimming two defenders in the AshGold goal area but his shot was blocked.
Zdravko Lugarosic altered his side by making two substitutions but they failed to make an impact as Kotoko continued to push for the third.
Kotoko then turned defence into attack in the 89th minute to score the third goal through Michael Anaba.
The goal finally killed off any hope of AshGold staging a comeback.