The Toffees blew away their Swiss opponents in a sensational first half of attacking football, with the Belgian striking twice and Seamus Coleman’s close-range effort making it 3-1 at the break.
Guillaume Hoarau had interrupted a brilliant start to the game when he curled home from 25 yards but Lukaku soon evened it up – and the Toffees kicked on from there.
It was Everton who took their chances, Coleman tapping home before Lukaku added his second - and the Blues’ record signing then completed his treble after the interval.
John Stones saw red for hauling down Hoarau, conceding a penalty in the process, but the Young Boys frontman saw his spot-kick clear Tim Howard’s crossbar, once more confirming it was to be Everton’s night.
They went close as early as the third minute. The ball was patiently worked this way and that before finding its way to Bryan Oviedo. The Costa Rican swung over a perfect cross for the stooping Romelu Lukaku, but Yvon Mvogo was down quickly to smother the ball around the post.
However, it was the hosts who drew first blood. Raphael Nuzzolo passed to Hoarau and the big Frenchman curled an exquisite shot around Howard and into the net.
The goal admittedly came against the run of play with Everton enjoying plenty of the ball. Soon they were back threatening the home goal. Stones played the ball up to Lukaku, who turned well and drew a second good save out of Mvogo. Barkley was then denied by the young custodian.
On 23 minutes, Lukaku won his battle with Mvogo. Promising build-up play saw the ball worked out left to Barry, who lofted over a cross for the big Belgian to guide a header past the Young Boys keeper.
If the 3,700 travelling Evertonians thought that was good, the second goal was even better. Oviedo, Barkley and Naismith scintillatingly combined to allow the latter to sweep a pass across goal where Coleman was on hand to slide in and score.
Everton had their tails up. ‘We shall not be moved’ echoed from the away end. Naismith was clipped 25 yards from goal but Mirallas whipped the resultant free-kick over the bar.
Young Boys, however, came roaring back and Hoarau struck a fine volley that had Howard sprawling, with the American pouncing on the rebound from a diving Nuzzolo.
Phil Jagielka was then on hand to superbly head away a teasing Jan Lecjaks cross under pressure from several Young Boys players.
Hoarau was causing problems. The Frenchman was a whisker away from adding to his tally, guiding a header inches wide as the contest became an enthralling back and forth affair.
And it was Everton who struck again. Lukaku broke and drove forward. Via Naismith, the ball was played out to Barkley, whose cross fell to Oviedo. The Costa Rican’s back heel was perfect for Barry and he squared for Lukaku to complete the move he started with a simple finish.
The Blues were almost in on goal seconds later but Lecjaks outmuscled Mirallas before the winger could shoot.
The momentum swung back the way if Young Boys once more – McCarthy got a huge thump on the back from Howard for a quite extraordinary clearance of the line from a venomous Sekou Sanogo effort seconds before half time.
And with that, the whistle went for the break.
While the temperature plummeted inside the Stade de Suisse, the desire for more Everton goals did not. Oviedo swung over a good cross for Lukaku, only for the ball to end up with Mirallas. The winger took a touch to control but dragged his shot wide.
Unfortunately, Oviedo’s night came to an early end on 56 minutes. Doing excellently to defend against Steffen, the left-back instantly signalled the bench, pointing at his hamstring. On came Luke Garbutt in his place.
The blow was short-lived. Lukaku broke clear of the Young Boys defence to clip the ball over Mvogo to complete his hat-trick.
Credit to the hosts, they came back with renewed vigour, Lecjaks fizzing a drive over Howard’s bar.
Their cause was helped by the sending off of Stones just past the hour. Losing possession to Hoarau, the Frenchman bore down on goal only for the recovering Blues defender to haul him to the ground.
Up stepped the Hoarau to further punish the visitors from the spot – only for him to sky his spot-kick.
Even with 10 men, the Toffees still posed a threat. Lukaku went close to grabbing a fourth, just failing to latch onto the end of a Garbutt centre.
Having waited an age to come on, Antolin Alcaraz replaced McCarthy to shore up the Blues defence, allowing stand in centre back Barry to step back into midfield.
Young Boys substitute Alexander Gerndt saw a volley comfortably saved as the hosts tried to apply pressure in the final 20 minutes. The striker was then denied by brilliant block from Alcaraz.
Everton were always dangerous on the counter attack and Lukaku was denied a fourth by Mvogo with five minutes remaining.
The big striker was replaced by Christian Atsu seconds later, proud of an exceptional night’s work, something that could be said about every one of his team-mates.