He told U.S. District Judge Jed S. Rakoff that he did not intend for the devices to explode but was aware of the risk that they might.
"In October 2018, I made devices that were created to look like pipe bombs and sent them in the mail", Sayoc said in court.
He was charged with 30 counts, including criminal mailing of explosives and use of weapons of mass destruction. In exchange for his guilty plea, prosecutors dropped a charge that carried a mandatory life sentence.
Sayoc has been accused of mailing 16 pipe bombs, some of which were sent to former Presidents Barack Obama and Bill Clinton, former Vice President Joe Biden, former Secretary of State Hillary Clinton, billionaire financier George Soros, actor Robert De Niro, several members of congress, and CNN offices in NY and Atlanta.
Devices were also mailed to CNN offices in NY and Atlanta. The man was confiscated by US authorities on October 26, 2018, during the investigation into a series of parcel bombs sent to critics of Trump.
His attorney had entered a plea of not guilty on his behalf in November.
He'd been living in a van covered with Trump stickers and images of Trump opponents with crosshairs over their faces.with crosshairs over their faces.
People who knew Sayoc have described his peripatetic existence, saying that he lived for years out of his van while working as a DJ or bouncer at strip clubs.
Each device, Sayoc said, consisted of a plastic pipe with a digital alarm clock and attached wires.
"What would prevent, for example, powder from fireworks from exploding?" the judge asked.
"I'm extremely sorry", he said.
The first bomb was discovered October 22 in a padded envelope in a mailbox at an estate in New York City's northern suburbs owned by the billionaire George Soros, a liberal political activist and frequent subject of conspiracy theories.
The slew of charges relates to 16 package bombs Sayoc sent from a Florida post office to leading Democrats as well as the Manhattan offices of CNN. One, addressed to former Central Intelligence Agency director John Brennan, was sent to CNN in NY.
Mr Sayoc is accused of mailing 16 pipe bombs to 13 targets including ex-President Barack Obama last October. The most recent device was intercepted en route to New Jersey Senator Corey Booker on Friday.
Over several days, investigators tracked the packages to a mail center in Florida.
Sayoc mailed 16 improvised explosive devices to 13 targets around the United States, including 11 current or former USA government officials, the U.S attorney's statement says. He grew up in North Miami Beach and did a variety of odd jobs, including working as a male stripper.
Sayoc, born in Brooklyn, struggled to make ends meet in South Florida.