When it came to the campaign finance violations, Cohen implicated the President directly.
He told the court that he worked with Trump to pay off two women to keep their stories of alleged affairs with Trump from becoming public before Election Day.
In a statement, Trump lawyer Rudy Giuliani said: "There is no allegation of any wrongdoing against the President in the government's charges against Mr Cohen. It is clear that, as the prosecutor noted, Mr Cohen's actions reflect a pattern of lies and dishonesty over a significant period of time."
Cohen is the fifth Trump associate to have pleaded guilty or be charged with criminal wrongdoing since Trump took office, including his former national security adviser, his deputy campaign chairman and a former campaign policy adviser.
Cable television played Cohen's plea in an extraordinary legal split screen, as a Virginia jury convicted former Trump campaign chairman Paul Manafort on eight counts in his bank and tax fraud trial.
The jury in Alexandria, Virginia, convicted Manafort on eight of the 18 tax and bank fraud charges against him and said it was deadlocked on the other 10. Judge T.S. Ellis said he would declare a mistrial on those other charges.
Trump reacted by saying the Manafort conviction "has nothing to do with Russian collusion," and called it "a disgrace".
The charges in the Manafort trial involved the former campaign manager's personal finances and were not related to Special Counsel Robert Mueller's investigation into Russian interference in the 2016 election. But Manafort's conviction on eight counts, in the first trial to emerge from Mueller's probe, was a major victory for the Special Counsel.
Manafort was convicted of filing a false tax return in each of the years from 2010 through 2014 as well as not filing a form to report a foreign bank account as required in 2012.
He was also found guilty of two instances of bank fraud, related to a US$3.4 million loan from Citizens Bank and a US$1 million loan from Banc of California. The jurors could not agree on three counts for not filing a form to report a foreign bank account, and seven for committing bank fraud or conspiring to commit bank fraud.
As the Alexandria jury was delivering its verdict on Manafort, Cohen was in a Manhattan courtroom, admitting to a range of offences that emerged as part of a separate investigation.
Cohen - long the self-professed "fixer" for Trump - pleaded guilty after prosecutors claimed he risked more than a dozen years in prison, according to a person familiar with the matter.
While Cohen's plea deal did not include a promise to cooperate with investigators against any other individuals, his description of his acts implicates not just himself but Trump and others.
Cohen told the court that "in coordination with and at the direction of a candidate for federal office," he and the chief executive of a media company worked in the summer of 2016 to keep an individual from publicly disclosing information that could harm the candidate. And he said he worked "in coordination" with the same candidate to make a payment to a second individual.
"I participated in this conduct . . . for the principal purpose of influencing the election," he said.
The details he described matched payments made to former Playboy model Karen McDougal and adult-film star Stormy Daniels. Both have alleged that they had sexual encounters with Trump, which he has denied.
In August 2016, McDougal was paid US$150,000 by AMI, the parent company of National Enquirer, for the rights to her story, which the company then shelved. In October 2016, Cohen used a home-equity line of credit to finance a US$130,000 payment to Daniels.
Trump had previously denied knowledge of the Daniels payoff, and Giuliani said Trump did not know about it at the time. But Cohen said today that Trump repaid him the money for the purpose of influencing the campaign.
AMI officials did not respond to requests for comment.
Asked by Pauley whether he knew what he did was wrong and illegal, Cohen said yes.
Lanny Davis, a lawyer for Cohen, said in a statement that Cohen pleaded guilty "so that his family can move on to the next chapter."
"Today he stood up and testified under oath that Donald Trump directed him to commit a crime by making payments to two women for the principal purpose of influencing an election," Davis added. "If those payments were a crime for Michael Cohen, then why wouldn't they be a crime for Donald Trump?"
According to court filings, Cohen failed to report US$4 million in income from 2012 to 2016 to avoid paying taxes on money he earned, mostly through interest and taxi rental payments.
He also concealed US$100,000 he made in selling a piece of property in Ocala, Florida, in 2014, a US$30,00 in profit he made for arranging the sale of a couture Birkin handbag and US$200,000 in consulting fees he made from an assisted-living company, according to filings.
As part of his plea deal, Cohen agreed to file corrected tax returns and pay US$1.5 million to the Internal Revenue Service.
Cohen left the courthouse shortly after the hearing ended, entering a black Buick as a protester across the street screamed, "Lock him up."
Robert Khuzami, the deputy US attorney for the Southern District of New York, said in a statement that rather than respect the law as a lawyer, Cohen "chose to break the law, repeatedly over many years and in a variety of ways. His day of reckoning serves as a reminder that we are a nation of laws, with one set of rules that applies equally to everyone."
The case against him stems in part from Mueller, who examined Cohen's role in at least two episodes involving Russian interests, according to people familiar with that probe.
However, special-counsel investigators have indicated to federal law enforcement officials that the office does not require Cohen's cooperation for its probe, according to two people familiar with their work.
The Cohen investigation first burst into public view in April, when FBI agents searched his New York office, home and hotel room. The searches - in which agents collected all of Cohen's phones and electronic devices - set off panic in the White House that federal investigators were looking into Trump's business dealings and communications with Cohen.
Since then, the probe has led to revelations about how Cohen sought to squelch negative stories about Trump and then leverage his access to the President.
After the raid, Giuliani acknowledged that the President had made several payments reimbursing Cohen for the US$130,000 settlement with Daniels.
Leaked documents showed that Cohen was paid millions last year by companies such as AT&T and Novartis to provide advice about the new administration.
Cohen had been under scrutiny by federal prosecutors starting in the northern autumn of 2017, when Mueller's team came across some unusual financial transactions and loans Cohen had obtained.
The Special Counsel referred the matter to the U.S. attorney's office for the Southern District of New York.
