Fresh from a political win on Monday in the Iowa caucuses, the Republican presidential frontrunner detoured to a Manhattan courtroom for what amounts to the penalty phase of a civil defamation lawsuit stemming from Carroll's claims he sexually attacked her in a department store dressing room.
Prospective jurors were told the trial was likely to last three to five days.
Opening statements come next.
Trump did not attend the previous trial in the case last May, when a jury concluded he had sexually abused Carroll and awarded her $US5 million ($A7.6 million) in damages.
In light of that verdict, Judge Lewis A Kaplan told prospective jurors the trial beginning on Tuesday would focus only on how much money, if any, Trump must pay Carroll for comments he made about her while president in 2019.
For purposes of the new trial, it had already been determined that Trump "did sexually assault Ms Carroll," Kaplan said, prompting Trump to shake his head from side to side.
The former president was sitting at the defence table, flanked by his lawyers, about four metres from Carroll and her legal team.
They did not appear to speak or make eye contact.
As the day began, Kaplan rejected the defence's request to suspended the trial on Thursday so Trump could attend his mother-in-law's funeral - part of a combative exchange in which Trump's lawyers accused the judge of thwarting their defence with pre-trial evidence rulings they contend were favourable to Carroll.
"I am not stopping him from being there," the judge said, referring to the funeral.
Trump lawyer Alina Habba responded: "No, you're stopping him from being here."
Habba told the judge that Trump plans to testify.
Kaplan said the only accommodation he would make is that Trump can testify on Monday, even if the trial is otherwise finished by Thursday.
The judge previously rejected Trump's request to delay the trial a week.
Trump sat attentively, glaring and scowling at times, as about six-dozen prospective jurors filed into the courtroom and spent more than an hour responding to questions posed by the judge covering everything from their prior involvement with the judicial system to their political beliefs.
He twisted around in his chair to get a look at two prospective jurors - a man and woman - who stood when asked if they agreed with his contention that the 2020 election was rigged, and again when three people in the pool indicated they felt the former president was being treated unfairly by the court system.
The process offered a window into the political beliefs of a microcosm of New Yorkers, drawn from a pool that includes Manhattan and northern suburban counties.
Some noted personal connections to Trump or his adversaries.
One woman said she had done publicity for his daughter's company.
Another said her father provided moving services for some of Trump's buildings.
Both said they could be fair and impartial and remained among prospective jurors.
Jurors selected for the trial will remain anonymous, even to the parties, lawyers and judicial staff, and will be driven to and from the courthouse from an undisclosed location for their safety, Kaplan said.
Carroll, 80, plans to testify about the damage to her career and reputation that resulted from Trump's public statements.
She seeks $US10 million ($A15 million) in compensatory damages and millions more in punitive damages.
If Trump testifies, he will be under strict limits on what he can say.
Because of the prior verdict, Kaplan has said, Trump cannot get on the witness stand and argue that he did not sexually abuse or defame Carroll.
