The Easter Road youngsters dominated the early stages and Oli Shaw reached a cross from Callum Donaldson after three minutes but sent his header just over.
Donaldson should have scored soon afterwards when Sean Mackie whipped over a cross from the left but his fellow wing-back slid a first-time effort wide.
Aberdeen gradually grew into the game and Bruce Anderson wriggled clear on 14 minutes only to shoot straight at Maciej Dabrowski in the Hibs goal. The young Dons did get their noses in front two minutes later thanks to a solo goal by Connor McLennan.
Sam Roscoe picked out the striker wide on the right with a 40-yard pass and McLennan worked his way past Mackie before darting towards the Hibs goal where he ended a mazy dribble with a close-range finish.
The Edinburgh side looked to have hit back in glorious style midway through the opening half when Fraser Murray let fly from 25 yards out but his shot came crashing back off the bar.
Hibs did level on 33 minutes when Fraser Murray sent over a teasing ball that was too tempting for Joe MacPherson to ignore and the Aberdeen defender could only guide the ball into his own net.
Aberdeen replaced McLellan with Miko Virtanen at the break but it was Hibs who restarted better with Jamie Gullan sending a shot just wide.
Anderson had a glimpse of goal just before the hour mark after persistence by Ethan Ross but his drive was blocked on the six-yard line by a line of Hibs defenders.
Gullan thought he had given Hibs the advantage eight minutes later when he cracked a shot goalward from eight yards out but David Craddock produced a fine save, and Frank Ross almost drilled Aberdeen ahead a minute later from the edge of the box.
The third goal of the game went the way of Hibs on 72 minutes when Ben Stirling fired over from the right after a free-kick had not been cleared and Porteous sent a thumping header home from six yards.
The game was put out of Aberdeen’s reach seven minutes later when a shot by Shaw was blocked and the ball ran straight to Gullan, who tapped in.