The 19-year-old was handed just his second start but repaid manager Pat Fenlon's faith with his sensational strike.
The final SPL meeting of the sides this season looked set to end in a fourth stalemate after Leigh Griffiths' stunning free-kick two minutes after half-time cancelled out Darren Barr's 44th-minute opener for Hearts.
It was the defender's first goal since he struck the first in the Jambos' 5-1 rout of their rivals in last May's William Hill Scottish Cup final.
But Hibs - who are preparing for their second successive final appearance later this month - ensured they retain the bragging rights as they added to their January cup triumph with a second victory over Hearts this season as well as overtaking Gary Locke's men to steal ninth place in the table.
Chris Humphrey was the main man for the SPL runners-up, setting James McFadden up for the opener in the seventh minute before doubling the Steelmen's lead seconds before the interval with a superb solo goal.
Amid some steady pressure from County after the break, McFadden missed a great chance to make it 3-0 but that would have been barely a true reflection on a game in which little went right for the Highlanders.
County go into the last game of the season next week against Inverness four points behind and with only local pride to play for as Terry Butcher's side and St Johnstone, who host the Steelmen, battle it out for the last European spot.