Olympic downhill champion Mayer posted 1 minute 31.53 seconds, 0.23 seconds up on super-g world championship bronze medallist Adrien Theaux of France.
It was a third World Cup career victory and a first in super-g for 24-year-old Mayer, who headed an Austrian downhill sweep of the podium in Saalbach Saturday.
Kjetil Jansrud of Norway was third at 0.27 seconds to make up ground on Austrian Marcel Hirscher in the overall World Cup standings.
However Hirscher, who has a 116-point lead ahead of the last 10 races – five speed and five technical – remains favourite for a fourth successive overall title.
Jansrud also extended his lead in the discipline standings by 73 points over Italy’s Dominik Paris, who was 14th.
Slalom specialist Hirscher, making one of his few super-g starts, was meanwhile 17th.