In a message on his platform Truth Social, Trump touted what he called a hugely successful record as president and said "I WILL THEREFORE NOT BE DOING THE DEBATES!"
The first debate in the race for the 2024 Republican presidential nomination is scheduled for Wednesday in Milwaukee, Wisconsin.
In his post, Trump noted the latest in a wave of polls showing him far, far out ahead of the Republican field, including one by CBS News published Sunday.
It said 62 percent of those polled for the survey would vote for him even though he has been indicted four times this year, including on charges he tried to subvert US democracy by scheming to overturn the 2020 election and stay in power despite his loss to Joe Biden.
Trump's closest contender in the CBS poll was Florida Governor Ron DeSantis at 16 percent. The rest of those in the field are polling in the single digits.
Trump wrote that DeSantis is "crashing like an ailing bird."
"The public knows who I am & what a successful Presidency I had," Trump said, citing issues including energy, border security and the military, and the economy.
The 77-year-old former president, who is rarely out of the headlines, had been vocal about possibly skipping the debate in the midwesten city of Milwaukee, wary of sharing the limelight with lower-polling rivals.
The New York Times reported Friday that Trump had told aides he was planning to upstage his rivals by skipping the event, organized by Fox News, and instead sit for an online interview with one of Fox's former hosts, Tucker Carlson.
Even in his absence, Trump will be ripe for broadsides from opponents over the four criminal and three civil trials he faces involving allegations before, during and after his scandal-plagued presidency.
"Obviously, his legal issues are affecting this race," Fox News host Bret Baier, who will be moderating the debate, told the Milwaukee Journal Sentinel.
"All these candidates have been asked non-stop about what's happening in courtrooms around the country. So he'll be a part of this debate whether he's there or not."
Seven other candidates have qualified for the debate, including state governors DeSantis and Doug Burgum, former vice president Mike Pence, Trump's UN ambassador Nikki Haley and South Carolina Senator Tim Scott.
While Trump dominates the field, polling well above his opponents, some allies worry that a no-show could give his rivals a chance to create a viral moment and gain momentum.