Wearing a dark blue suit and red tie, Trump, 76, exhibited little emotion on his face when he waved to a crowd assembled outside the courthouse after he was driven in a motorcade from his New York residence at Trump Tower.
Trump, who has called the charges politically motivated, held his fist in the air in a gesture to reporters as he departed Trump Tower.
Looking somber, Trump said nothing as he walked past police and through a hallway in the courthouse before entering the courtroom for the arraignment proceeding.
The first sitting or former US president to face criminal charges, Trump was indicted by a Manhattan grand jury last week in a case stemming from a 2016 hush-money payment to porn star Stormy Daniels.
From his motorcade, Trump posted on social media: "Heading to Lower Manhattan, the Courthouse. Seems so SURREAL - WOW, they are going to ARREST ME. Can't believe this is happening in America."
Trump entered the plea at an arraignment proceeding before Justice Juan Merchan. At an arraignment, a defendant hears charges and can enter a plea. Trump was fingerprinted but no mugshot photo was taken, according to a Twitter post by a New York Times reporter.
Trump left the court after a hearing that lasted almost an hour.
A motorcade escorted Trump from the courthouse in Lower Manhattan, and was expected to return to his home in Florida.
He ignored questions from reporters on his way out.
On social media, Trump ahead of the arraignment renewed his attacks on Merchan, who last year also presided over a trial in which Trump's real estate company was convicted of tax fraud.
Trump, who served as president from 2017 to 2021, in November announced a bid to regain the presidency in 2024 in a bid to deny Democratic President Joe Biden, who beat him in 2020, a second term in the White House.
On a cool and sunny early spring day in the most-populous US city, Trump supporters and detractors were separated by barricades set up by police to try to keep order, though there were some confrontations.
"Let's keep it civil, folks," a police officer told them.
Hundreds of Trump supporters, at a park across from the Manhattan courthouse, cheered and blew whistles, outnumbering his detractors. The Trump critics held signs including one of Trump dressed in a striped jail uniform behind bars and another that read, "Lock Him Up."
Typically, people facing arraignment are fingerprinted and have mugshot photographs taken. The court appearance was likely to be brief.
"It won't be a long day in court," Joseph Tacopina, one of Trump's lawyers, said on ABC.
Yahoo News late on Monday reported that Trump would face 34 felony counts for falsification of business records.
Any trial is at least more than a year away, legal experts said. Being indicted or even convicted does not legally prevent Trump from running for president.
Five photographers will be admitted to the courtroom before the arraignment starts to take pictures for several minutes. Trump's lawyers had urged a judge to keep them out, arguing they would worsen "an already almost circus-like atmosphere."
Bragg, a Democrat who led the investigation, was set to give a news conference after the arraignment. Trump and his allies have portrayed the case as politically motivated.
Former US president Donald Trump appears in the Manhattan courthouse. Photo: POOL