There was no immediate reaction from Beijing, but earlier Monday the Chinese foreign ministry had threatened "resolute countermeasures" if any such boycott were implemented.
The decision was swiftly welcomed by politicians in the US, where President Joe Biden has been under pressure to speak out against Chinese rights abuses.
White House Press Secretary Jen Psaki said the Biden administration would not send any diplomatic or official representation to the Beijing Games given China's "ongoing genocide and crimes against humanity in Xinjiang and other human rights abuses."
"The athletes on Team USA have our full support. We will be behind them 100 percent as we cheer them on from home."
Campaigners say that at least one million Uyghurs and other Turkic-speaking, mostly Muslim minorities have been incarcerated in camps in Xinjiang, where China is also accused of forcibly sterilizing women and imposing forced labour.
Sending official representation to the Olympics would signal that, despite China's "egregious human rights abuses and atrocities in Xinjiang," the Games were "business as usual," Psaki said.
"And we simply can't do that," she continued.
'Powerful rebuke'
Bob Menendez, the chair of the US Senate foreign relations committee, welcomed the decision he called "a powerful rebuke of the Chinese Communist Party's campaign of genocide in Xinjiang."
He called on "other allies and partners that share our values to join with the United States in this diplomatic boycott."
Human Rights Watch called the decision "crucial" but urged more accountability "for those responsible for these crimes and justice for the survivors."
Earlier Monday Chinese foreign ministry spokesman Zhao Lijian warned the Games were "not a stage for political posturing and manipulation."
Speaking at a regular press briefing on Monday in response to weekend US media reports that a boycott could be imminent, he vowed that "If the US is bent on having its own way, China will take resolute countermeasures."
Coming just six months after the pandemic-delayed Tokyo Summer Games, the Winter Olympics will be held from February 4 to 20 in a "closed loop" bubble because of Covid-19 restrictions.
