The incident happened during a downhill slalom race at the World Championships being held at Madonna di Campiglio in northern Italy's Dolomite mountains.
As Hirscher raced downhill the robotic aircraft malfunctioned and fell, slamming into the piste just behind the 26-year-old defending world champion.
According to Fis race director Markus Waldner, an initial investigation suggests that the drone was brought down by a sudden burst of RF interference from an unknown source. Its batteries were in excellent condition.
Drones have now been banned at Fis meets until a full study is conducted into their safety.
The close call was captured on video below.
Despite being nearly taken out by the falling drone, Hirscher still managed to race to a second-place finish, just behind Henrik Kristoffersen of Norway.
But the accident left the defending world champion furious.
“This is horrible,” he told reporters after the race. “This can never happen again – there could have been a serious injury.”
Hirscher currently leads the standings at the World Championships and is on course to notch up his fifth straight title.