Fenniger also won the super-combined race in the Bulgarian resort on Sunday and her second win in two days means that she is now just 44 points behind long-time leader Tina Maze of Slovenia in the overall World Cup standings.
The 25-year-old Austrian, winner of the super-G gold medal at the recent World Chmpionships in the United States, clocked 1 minute 14.59 seconds, 00.16secs clear of Maze with US speed queen Lindsey Vonn third at 00.28secs off the pace.
The win also means that Fenniger now tops the supr-G standings, taking over from Vonn.
Maze at one stage had been leading the overall standings by as much as 370 points, but is without a World Cup win since mid-December and now faces a tough battle to hold off the charge of Fenninger with just three weeks to go until the season-ending races in Meribel, France.