On-loan Southampton winger Elyounoussi is enjoying a new lease of life with the Glasgow giants and opened the scoring with a powerful header from James Forrest’s cross before Callum McGregor tapped into an empty net from Odsonne Edouard’s chip over Hibs goalkeeper Chris Maxwell.
Melker Hallberg briefly cut the Edinburgh side’s deficit in half before Edouard was the creator again for Elyounoussi to smash home his seventh goal in seven games.
“I thought he was outstanding. His best performance since he’s come in,” said Celtic manager Neil Lennon of Elyounoussi, who struggled to make an impact in his one season at Southampton after a big money move from Basel.
“His intelligence on the ball and his link-up play and his fitness levels are incredible.
“What you’re seeing now is the player that Southampton spent £16 million for. We’re delighted he’s making us better and we’re delighted we’re making him better.”
Forrest and Elyounoussi then hit the woodwork early in the second half as Celtic threatened to run riot.
But when the fourth goal did arrive, Hibs were masters of their own downfall as Maxwell flapped at a corner and Celtic captain Brown swept home the first of a rare double.
Hibs responded quickly through Florian Kamberi, but it was too little, too late with the pressure on manager Paul Heckingbottom ramped up once more with his side just a point off the bottom of the Scottish Premiership.
“It’s the league where we’re judged,” said Heckingbottom.
“We all know things could have been different, could have been so much better in the league, but it’s not so we have to put that right.”
Brown sealed a 30th straight domestic cup victory for the holders in stoppage time at the second attempt after Maxwell did well to block his first effort.
Celtic will now face old rivals Rangers or Hearts, who face off in the second semi-final on Sunday, for the first silverware of the Scottish season on December 8.
