Anthony, 27, became the first Australian to earn two Winter Olympics gold medals when she overtook American Jaelin Kauf under heavy snow in the northern Italian town of Livigno. Kauf earned silver, and bronze went to fellow American Elizabeth Lemley.
Dual moguls is a new sport at the Olympics, pitting skiers together in a head-to-head elimination format in which two competitors race side-by-side through parallel bump fields. Speed counts, but so do turns and aerial manoeuvres.
Anthony crossed the finish line a fraction of a second before Kauf but had to wait for the judges' final assessment.
She smiled and pumped her arms in the air when she saw she had earned a score of 20, compared to Kauf's 15. A throng of Australian supporters cheered and waved yellow inflated kangaroos on the side of the mountain.
At the medal ceremony, Anthony broke into a wide smile as she celebrated her historic second Olympic gold.
Anthony had been the favourite to win the singles but wobbled out of line in her second run to finish eighth. In the single moguls, riders tackle the course solo, and the highest score wins.
Heavy snow fell throughout the dual moguls finals, hindering visibility for the skiers.
Kauf's second-place ranking gave the 29-year-old her third Olympic silver medal. She finished second in the singles at the Milano Cortina Games and at Beijing in 2022.
"I was really going for gold, but I guess 'Silver Jae' has a ring to it, so I'm living up to the name," Kauf said.
The 20-year-old Lemley, the surprise gold medallist in the singles, made it to the podium in the dual moguls despite a crash in the semi-finals.
Singles bronze medallist Perrine Laffont of France finished fourth in the dual event.
Italian Manuela Passaretta, aiming to impress an enthusiastic home crowd, made an early exit after skiing out of bounds near the start in the first round.