Knowing that a victory would confirm a top-two finish in Group G, the holders made light work of their Swiss counterparts, who succumbed to a pair of Erling Haaland goals either side of a slick Phil Foden effort and barely ventured into the City half throughout the 90 minutes.
There was both good and bad news for Man City on the injury front before kickoff, as Haaland was passed fit to start after his ankle scare over the weekend, but Manuel Akanji sustained a problem during the warm-up and was replaced in the backline by Kyle Walker.
An eleventh-hour alteration to the lineup had little effect on Man City's first-half supremacy, though, and the holders should have been ahead with six minutes gone as Jack Grealish squared for Rico Lewis inside the area, but Loris Benito deflected the teenager's goal-bound effort behind for a corner.
Benito's number one Anthony Racioppi was also earning his keep, making a 17th-minute double save from Walker's low free kick and Foden's follow-up, but the goalkeeper was let down by Sandro Lauper five minutes later.
The 27-year-old clipped Matheus Nunes inside the area right under the referee's nose, and faced by a wall of fervent Young Boys supporters, Haaland stepped up and convincingly sent Racioppi the wrong way to break the deadlock.
Haaland ought to have doubled his tally for the evening in the 36th minute as Kyle Walker fizzed a low delivery to the Norwegian at the back post, but the ball took a slight nick off of a Young Boys defender, and Haaland could only shin the ball into Racioppi's grateful arms.
The visitors - who offered nothing whatsoever in the final third - were seemingly happy to head into the break with just a one-goal deficit to make up, but Man City's pressure eventually told again in first-half injury time thanks to an honest piece of play from Foden.
After latching onto Grealish's curling ball out to the right, Foden could have easily gone down in the box after Ulisses Garcia tapped the back of his legs, but the Englishman carried on and calmly rolled home into the side of the net.
Despite his side's predicament, Young Boys skipper Mohamed Ali Camara had the cheek to seemingly ask for Haaland's shirt as the players headed into the tunnel, but with a fresh jersey on, the 23-year-old put the result beyond any doubt just six minutes after the restart.
With several black and yellow shirts around him, Lewis managed to pick a pass out into the centre, where Mateo Kovacic sensibly skipped out of Haaland's way, and the Scandinavian picked out the far corner with a fierce 20-yard drive for Man City's 250th Champions League goal - a milestone reached in a record low 119 games.
Things went from bad to worse for Raphael Wicky's team just two minutes after Haaland completed his brace, as Lauper - who was already on a yellow card - capped off a disastrous evening with an awful studs-up tackle on Nathan Ake, reducing his side to 10 men for the remainder of the second half.
The raucous Young Boys crowd would not let the scoreline dampen their spirits, and City understandably took their foot off the gas as the clock wound down, but Nunes spurned a glorious chance to add number four in the 81st minute, prodding wide at the back post from a couple of yards out.
RB Leipzig's 2-1 win over Red Star Belgrade means that City retain a three-point lead over the German side, whom they need only draw against on the penultimate matchday to confirm a first-placed finish, while Wicky's men have dropped to fourth place, behind Red Star on goal difference.
Pep Guardiola's side now have a blockbuster Premier League trip to Chelsea on the agenda this Sunday ahead of the international break, while Young Boys host Luzern in a Swiss Super League clash on Saturday evening.