Vancouver will play the Montreal Impact for the Canadian national club championship in a two-leg final. The first match will be on Aug. 12 and the second will be Aug. 26.
The Whitecaps won the two-leg semifinal series 3-2 on aggregate after a 1-1 draw in Vancouver last week.
Pedro Morales gave the Whitecaps an early 1-0 lead Wednesday on a penalty kick in the seventh minute of the game.
Tomi Ameobi tied it up for Edmonton in the first minute of injury time before Laba put away the winner in the 97th minute.
Edmonton nearly tied it 1-1 in the 12th minute when Ameobi found himself six yards out of the goal, but couldn't connect and seemed to step on the ball after Lance Laing had sent in a cross.
The Whitecaps' best chance came in the 39th minute when Cristian Techera's curling shot went just wide from a tapped free kick.
Edmonton finally tied it in the 91st minute when Kendall Waston fouled Frank Jonke in the box and Ameobi fired home the penalty.
With extra time looming, the ball got to Laba in the box and he fired through the 'keeper's legs from a tight angle.
Montreal qualified for the national final after drawing Toronto FC 3-3 on aggregate but having two more away goals.