The young American is hoping to become the first woman to win both the discipline's world title and overall crown in successive seasons.
Shiffrin, who retained her slalom title at February's world championships in Colorado, now has a 90-point lead going into next week's World Cup finale in France.
"I think the first couple races of the season I was pretty arrogant and was like, 'I'm just going to win these, I guess.' And I didn't. I wasn't even close," said Shiffrin, who has won the slalom Crystal Globe two years running.
"When you're racing at a high level -- or doing any sport at a high level -- everybody's going for the win. I learned that I can't take my foot off the gas and expect to win. These last races, I was pushing everything. Any race that I won this season, I was giving my entire heart into it. I'm proud of that."
A day after her 20th birthday, Shiffrin won by a comfortable 1.41 seconds at Are in Sweden as she claimed the 14th World Cup win of her career, with Slovakia's Veronika Velez Zuzulova second and Czech Republic's Sarka Strachova third.
Slalom title rival Frida Hansdotter finished sixth in front of her home fans.
Tina Maze missed a chance to close the gap on overall World Cup leader Anna Fenninger, who did not race, as the Slovenian finished back in 16th.
Defending champion Fenninger has a 30-point lead following the Austrian's victory in Friday's giant slalom in Are, where Shiffrin was fourth and Maze 20th.
Fenninger has an 86-point lead in the giant slalom standings from fellow Austrian Eva-Maria Brem -- who was third on Friday -- while Shiffrin is another 35 points back.
Meanwhile, Marcel Hirscher clinched the men's giant slalom title ahead of the finals in Meribel as the Austrian finished second in Saturday's penultimate race in Slovenia.
The 26-year-old now has a 128-point advantage as he seeks to win his fourth successive overall title as closest rival Kjetil Jansrud finished 23rd in Kranjska Gora.
France's Alexis Pinturault won on Saturday to be second in the giant slalom standings ahead of American Ted Ligety and third in the overall competition.
Olympic champion Ligety has won the last two giant slalom Crystal Globes but has dropped off the pace after a disappointing second half of the season.
On Saturday, he was fourth behind France's Thomas Fanara.
"This is the first time since the change in the ski rules (after the 2011-12 season) that I've caught the globe in GS," Hirscher said. "For me, it was two years with a lot of thinking and disappointment against Ted.
"I was 2.7 seconds behind Ted in the first race with the longer skis. We realized that we are so far away from Ted and that was the beginning of a long way and a lot of work, a lot of test and some different setup things. Many people worked really hard for this success."