The double Olympic champ's 62nd World Cup career win means she is now joint-second on the all-time women's list with Austria's Annemarie Moser-Proll.
Lindsey Vonn tops the list with 82 victories, but surely won't be long before 24-year-old Shiffrin overtakes her compatriot.
Roared on by a partisan home crowd, Shiffrin's 51.98-second first run gave her enough of a lead to take the overall title, despite finishing fourth in the second run.
Perhaps it was her recent U.S. Air Force Thunderbirds training session that did the trick?
Shouldering lofty expectations
Victory was made all the sweeter for Shiffrin, after finishing third in Saturday's Giant Slalom.
There was also the weight of expectation that she had to overcome. The slalom is Shiffrin's favoured event, having been unbeaten since 2016. Killington is also considered her home mountain, so it's fair to say there was seismic pressure and expectation on her to perform.
In addition, Shiffrin is competing this season without her mother and coach by her side due to a personal loss.
Given these potential distractions, her closest slalom rival Petra Vlhova would have been hoping to avenge several close losses in recent history at Killington.
The Slovakian has finished second to Shiffrin at the North American venue over the last two years, and was actually in a good position to beat her last Saturday in Finland, before skiing out early in her second run.
However it wasn't to be for Vlhova, who had to settle for silver once more, while Sweden's Anna Swenn Larsson scooped the bronze medal.
Mikaela Shiffrin: Record-breaking machine
Shiffrin was youngest athlete to reach 60 World Cup victories, and is also the first skier male or female, to win across all six disciplines: slalom, parallel, giant slalom, super-G, downhill and alpine combined.
Last season, the Colorado native took home an unbelievable 17 World Cup victories, smashing the previous record of 14 wins in a single season.
Earlier this month in Finland, she broke Swedish legend Igemar Stenmark's 32-year-old record for the most slalom wins in history (41).
These efforts, combined with two Olympic gold medals, further confirm her status as the most dominant skier in the world.