Forward Adrian Kempe and captain Gabriel Landeskog scored in rapid succession in the first period, while forward Filip Forsberg notched a goal in the second, and forwards Mika Zibanejad and William Nylander added two more in the third.
The Detroit Red Wings winger Lucas Raymond recorded three assists, helping on Landeskog's goal and in both of the third-period tallies.
The perennial medal contenders were a surprise entry in the qualification playoffs, after they finished a shocking third in their Group B, missing one of four automatic qualifying spots in the quarter-finals and the day off that goes with it.
It may have taken them another game to reach the final eight, but they wasted no time at Santagiulia Area on Tuesday, as a shot from Joel Eriksson Ek bounced in off Kempe's skate and Landeskog swiped the puck in again just 41 seconds later to set the tone.
"This is when the fun begins," said Landeskog. "It's important for us to regroup after this one, obviously recognise what we did well but understanding how our opponent's going to go up another level tomorrow and recognise what a great opportunity it is to see what we're made of."
They added to the lead midway through the second period, when alternate captain Erik Karlsson sent a superb pass to Forsberg, who tapped it in.
Latvian forward Eduards Tralmaks clawed one back with his third goal of the Games, pushing a rebound over the leg of Swedish goalie Jacob Markstrom, but Sweden put their foot on the gas from there.
Longtime New York Rangers centre Mika Zibanejad swatted one into an open net six minutes into the final period, and Nylander guided the puck beautifully around Latvian goalie Elvis Merzlikins to finish the scoring.
Sweden will play the United States on Wednesday for a spot in the last four, in a quarter-final meeting that has the feel of a heavyweight bout between two of the pre-tournament favourites.