Bale set Wales on their way with the opener in the first half before creating the second for half-time substitute Sam Vokes early in the second half.
Marc Janko set up a tense finale by pulling a goal back for Austria 15 minutes from time, but Wales held on for a morale-boosting win ahead of next month's World Cup qualifying double-header against Scotland and Croatia.
Austria almost got off to a flying start after just three minutes when Adam Matthews had to be alert to clear Marko Arnautovic's effort from a corner off the line.
Craig Bellamy, who has missed Wales' opening four World Cup qualifiers, had a chance to open the scoring on 16 minutes when he latched onto David Vaughan's pass, but the Cardiff forward failed to hit the target.
Wales made the breakthrough on 21 minutes when man of the moment Bale netted his 10th international goal for his country.
Liverpool midfielder Joe Allen picked out Bale with a fine through ball and the Spurs ace took the pass under control before firing home past Robert Almer in the Austria goal.
Wales had a lucky escape just past the half hour mark when West Ham new boy Emanuel Pogatetz bundled the ball home from Janko's header, but the goal was controversially ruled out for offside as replays showed it was the wrong decision.
The dangerous Arnautovic then forced Boaz Myhill into a fine save with a fierce swerving shot from distance on 36 minutes.
Austria were unlucky not to draw level on the stroke of half-time when David Alaba saw his stunning volley come back off the post with Myhill beaten.
Wales doubled their lead on 52 minutes when Bale turned creator to cross for substitute Vokes to powerfully head home.
Austria pulled a goal back 15 minutes from time when Alaba and Arnautovic combined and the latter crossed for Janko to head home at the far post.