Adams now becomes the first mayor in New York City history to be indicted while in office. If he were to resign, he would be replaced by the city's public advocate, Jumaane Williams, who would then schedule a special election.
A spokesman for the U.S. Attorney's Office for the Southern District of New York declined to comment.
"I always knew that If I stood my ground for New Yorkers that I would be a target - and a target I became," Adams said in a statement that implied he hadn't been informed of the indictment. "If I am charged, I am innocent and I will fight this with every ounce of my strength and spirit."
In a speech recorded at his official residence, Adams acknowledged that some New Yorkers would question his ability to manage the city while he fights the charges, but he vowed to stay in office.
"I have been facing these lies for months ... yet the city has continued to improve," Adams said. "Make no mistake. You elected me to lead this city and lead it I will."
Mayor Adams releases video statement responding to reports of indictment by federal grand jury
New York Gov. Kathy Hochul has the power to remove Adams from office. A spokesperson for Hochul said the governor is aware of the "concerning news reports" and is monitoring the situation, saying "It would be premature to comment further until the matter is confirmed by law enforcement."
Adams, the police officer turned politician, along with members of his inner circle has spent nearly a year under the cloud of federal investigations.
His cell phones were seized and, in recent weeks, the residences of some of his closest confidants were searched by federal agents working on several related corruption probes.
The mayor two weeks ago, accepted the resignation of Edward Caban, his handpicked police commissioner, after the authorities issued a subpoena for his phones.
The mayor's chief counsel, Lisa Zornberg, stepped down. This week, the schools chancellor, David Banks, announced plans to retire at the end of the year. Banks had also turned over his phone to federal authorities.
Banks's younger brothers, Philip, the deputy mayor for public safety, and Terence, also had their phones seized. David Banks's fiancée, Sheena Wright, the first deputy mayor, had her phone seized as well.
ALSO WATCH | ABC News' Aaron Katersky on what comes next after Adams' indictment
Mayor Adams indictment: What comes next
Adams has said that, as a former police officer, he has always followed the rules. He has also said he has known of no "misdoings" within his administration.
He has repeatedly said he wasn't aware of any wrongdoing, dismissing speculation that he would face charges as "rumors and innuendo."
The federal investigations into his administration first emerged publicly on Nov. 2, 2023, when FBI agents conducted an early morning raid on the Brooklyn home of Adams' chief fundraiser, Brianna Suggs.
At the time, Adams insisted he followed the law and said he would be "shocked" if anyone on his campaign had acted illegally. "I cannot tell you how much I start the day with telling my team we've got to follow the law," he told reporters at the time.
Days later, FBI agents seized the mayor's phones and iPad as he was leaving an event in Manhattan. The interaction was disclosed several days later by the mayor's attorney.
Other investigations have focused on city contracts and enforcement of regulations governing bars and clubs.
Only the second African-American to lead the nation's largest city, Adams had been hailed as the vanguard of a new generation of Democratic leader who could both support law enforcement and chart a progressive course coming out of a city-crushing pandemic.
He has led the city through a remarkable drop in violent crime after a COVID-era surge that led business leaders and residents to complain that New York was collapsing toward the bad old days of the 1980s.
Adams is not expected to appear in court until next week, according to sources.
ABC News and the Associated Press have contributed to this report.
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