The German led after both runs in Italy, eventually finishing almost a second clear of compatriot Fritz Dopfer.
Neureuther has made the podium on two occasions this term, but went one better on the final slalom event of 2014 to edge Dopfer by 0.82 seconds, with Sweden's Jens Byggmark a place back in third.
The 30-year-old Neureuther ensured his 10th World Cup victory in all disciplines with the help of an impressive first run.
A time of 50.60secs saw him set the pace at the midway mark ahead of Dopfer and the Swede Andre Myhrer.
"The first run was very demanding but positive, the snow was perfect and I'm having a very good feeling tonight," he said following the first run.
The likes of Norway's Henrik Kristoffersen and Frenchman Victor Jeandet-Muffat both impressed on the second run to assume the lead prior to Neureuther's final run.
However, last year's slalom runner-up kept his cool to turn in an even better time than his first - negotiating his second attempt in 49.97secs.
Defending slalom champion Marcel Hirscher could only finish seventh, allowing Neureuther to move top of the discipline standings.