The goal came after just three minutes when Hibs defender Harry Monaghan was short with a passback to keeper Sean Murdoch, allowing Hearts striker Smith to drive forward and slam the ball home.
Hearts coach Darren Murray was delighted with the result, saying: “It was a good performance from the players. They dominated the first half and did enough to win the game.
“Our movement was excellent and, although we didn’t score more, we probably should have.
“I’m not a big fan of the under-20 league but this was a good three points and a win over our old enemies.”
More than 700 fans saw some terrific football, with several first-team players such as Hibs’ Lewis Stevenson and Hearts’ Scott Robinson on show.
Hearts dominated the first half following Smith’s early goal, with right winger Billy King, switched to the left for tactical reasons, producing a man-of-the-match performance.
Hibs came out for the second half in more determined mood. They put more pressure on the Hearts defence and, after 55 minutes, Sam Stanton almost grabbed an equaliser. He picked up the ball in the inside right position before curling a shot just past the far post.
Hibs forced a series of corners – coming close on a couple of occasions – but gradually Hearts forced their way back into the game.
The young Jambos won a free-kick in a good position in the 75th minute. Robinson stepped up and drove the ball goalward only for Murdoch to produce a super save.
As the final whistle drew near, it was Hearts who were busy around the Hibs goalmouth with King producing a terrific run from the right wing to the left leaving a string of defenders in his wake before sliding the ball across the goalmouth only to see it scrambled clear by a nervous Hibs defence.
Hibs coach James McDonaugh was disappointed his side didn’t put Hearts under more pressure.
“One mistake cost us the game when they caught us cold on a poor pitch,” said McDonaugh.
“They had the better of the first half but we did enough in the second to at least get a draw.
“We should have put more pressure on them, though.
“When they scored we still had 87 minutes to get back into the game, so there was time. This league is a difficult one for everyone. We have to make constant changes in personnel and players don’t have time to bond together. For this game, we had to make three changes in the line-up and that’s unsettles the team.”
Hearts: Enckelman, Mullen, McHattie, D McGowan, McKay, Tapping, B King, Robinson, Smith, Holt, Walker. Subs: A King, Nicholson, McGhee, Oliver, Gordon, Hamilton.
Hibs: Murdoch, Gold, Kujabi, Stanton, Donaldson, Monaghan, Smith, Stevenson, Caldwell, Handling, Harris. Subs: Beaton, Paul, Wilson, Baptie, J Doyle, Court, Grant.