The 26-year-old jumped above Poland's French Open champion Iga Swiatek thanks to year-end adjustments in the standings.
Aryna Sabalenka said Tuesday that she wants to cap off a stellar year by returning to the top of the world rankings.
With Roger Federer retired and Rafael Nadal struggling to get back on court due to injuries, Novak Djokovic was the last man of that golden generation standing at Flushing Meadows, but the Serb crashed out in the third round to Australian Alexei Popyrin.
"I'm speechless right now. So many times I thought I was so close to get the US Open title. It has always been a dream of mine and finally I got this beautiful trophy," said Sabalenka.
Sabalenka sent down 34 winners to the 13 of the 23-year-old American in the tie.
Aryna Sabalenka detailed her current tennis philosophy on Tuesday, with the three-time Cincinnati Masters semi-finalist revealing she's quick to forget about her losses.
Osaka returned to the tour this year after 15 months of maternity leave for her daughter who turns one on Tuesday.
Russian teenager Mirra Andreeva became the youngest Grand Slam semi-finalist since 1997 with a shock victory over second seed Aryna Sabalenka, who was struggling with an apparent illness, at the French Open on Wednesday.
The current Australian Open champion arrived at Roland Garros as a top contender.
Formidable world number two Aryna Sabalenka blasted past Coco Gauff into the Australian Open final on Thursday to keep her title defence on track.
Fourth seed Gauff, attempting to become the first woman to back up a US Open title with a Grand Slam win in Australia since Naomi Osaka in 2018-19, has been almost as impressive.
Sabalenka ruthlessly handed 28th seed Tsurenko the dreaded "double bagel" in 52 minutes.
Elena Rybakina will head to the Australian Open full of confidence after demolishing world number two Aryna Sabalenka in the Brisbane International final on Sunday.
World number one Aryna Sabalenka sailed into the second round of the China Open with an imperious 6-1, 6-2 defeat of Sofia Kenin on Sunday.
Newly crowned world number one Aryna Sabalenka said Friday she is "super motivated" to finish the year in top spot as she prepares to compete in the China Open in Beijing.
Aryna Sabalenka fought back from the brink of defeat to overcome American 17th seed Madison Keys in a third-set tie-break and line up a US Open final against home favourite Coco Gauff.
New York has been sweltering in a heatwave this week, with high humidity and temperatures at Flushing Meadows on Wednesday hitting 35 degrees Celsius (95 Fahrenheit)
Alcaraz, looking to become the first man to successfully defend the title since Roger Federer in 2008, polished off British 26th seed Dan Evans 6-2, 6-3, 4-6, 6-3 in 3hr 11min
Women's tennis chiefs on Monday pleaded with spectators to show "understanding and respect" when Ukraine players refuse to shake hands with Russian and Belarusian opponents in protest at the ongoing war in their country.