Coming into the game, the Blues trailed the Canucks by one point for No. 1 in the conference and the league, but thanks to Luongo's 58th career whitewash, Vancouver now has 90 points, two more than the Eastern Conference-leading New York Rangers.
Alexandre Burrows scored the winner in the third while Chris Higgins added an empty-netter for the Canucks, who snapped a two-game slide.
Brian Elliott was the tough-luck loser as he gave up just one goal on 23 shots for the Blues, who had a four-game winning streak stopped.
The goaltenders put on a clinic through the first two periods with Luongo stopping 22 shots and Elliott turning away 18, but the Canucks got on the board 4:17 into the third.
Dan Hamhuis blasted a shot from the right point that went wide of the net, but it bounced back to the right side. From there, Burrows was able to knock it in for his 23rd goal of the season.
Luongo did the rest, stopping seven shots in the final frame with Higgins sealing the win with the net empty.
The loss drops St. Louis back to fourth in the Western Conference. The team has 87 points and is tied with Detroit for the Central Division lead, but Detroit has more wins and has played one less game.
St. Louis plays in San Jose on Saturday...Vancouver hosts Buffalo on Saturday...These teams split the season series...Both squads went 0-for-2 on the power play.