Heading into the event, 19-year-old Kristoffersen could already boost three podium finishes this World Cup season, although the top step had so far proved elusive.
But it was a case of fourth time lucky for the Norwegian as his time of 1:47.43 minutes was good enough for the gold, pipping home favourite Marcel Hirscher to the gong by 0.18 seconds.
Completing the final slalom World Cup podium was German Felix Neureuther who came home in 1:47.62 minutes.
Kristoffersen's victory closes the gap on Hirscher in the slalom World Cup standings, the Austrian now leading by 50 points as the Norwegian and Heureuther both sit on 370.
And in the overall World Cup standings Hircher is now just 22 points behind current leader Aksel Lund Svindal with the Norwegian absent from Schladming.