The Italian Alex Vinatzer won the bronze medal, three hundredths of a second ahead of the French Olympic champion Clément Noël, at the foot of the podium in the last event of the World Championships.
The Blues leave their Worlds with only two medals, won by Alexis Pinturault (combined gold, super-G bronze) in the first week.
"Pintu" only took 20th place in the slalom on Sunday.
Only 16th in a very tight first run, Kristoffersen (28) achieved the best time on a second tricky course to win his first crown of slalom world champion, after 23 victories in the discipline on the world circuit.
He had won the giant world title in 2019 in Are (Sweden).
Behind him, AJ Ginnis (28) created a huge sensation by giving Greece its first podium at the World Alpine Skiing Championships.
This "second zone" skier at world level announced his great form with a second place in the Chamonix slalom two weeks ago, there also a first Greek podium on the world circuit.
The Greek AJ Ginnis in Courchevel on February 19, 2023 © Jeff PACHOUD / AFP
Born to an American mother and a Greek father, Ginnis grew up in Greece and learned to ski on the slopes of Mount Parnassus.
Greek skier since 2020 after having worn the United States jersey for a time, he had a career cut short by six knee operations, the last of which was in August 2021.
© 2023 AFP