Sayoc pleaded guilty to sending explosive devices to critics of US President Donald Trump.
Sayoc, 57, sat through most of the proceeding with his mouth slightly open and his eyes locked on the judge.
None of the bombs exploded before being intercepted, and no one was injured. Sayoc, who lived in a white van adorned with right-wing political images supporting Trump and denouncing Trump's critics, was apprehended after an intense manhunt.
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.
No one was physically injured by the homemade pipe bombs, though Federal Bureau of Investigation officials said each device consisted of roughly six inches of PVC pipe, a small clock, a battery, wiring, and "energetic material" capable of exploding if exposed to heat, shock or friction.
Sayoc pleaded guilty to 65 felonies on Thursday in a Manhattan federal court with 16 of those charges of using a weapon of mass destruction.
Other targets included actor Robert De Niro and former Central Intelligence Agency directors John Brennan and James Clapper, who have criticized Trump, and Democratic donors George Soros and Tom Steyer, prosecutors said.
Nirav Modi: Billionaire jeweller arrested in London over India’s biggest banking fraud
India had approached Interpol regarding Nirav and in July of 2018, a red corner notice (RCN) was issued against him. India, which has been seeking Modi's extradition for months, welcomed the businessman's arrest.
But the deal lets either side argue for more or less time in the slammer at Sayoc's scheduled September 12 sentencing. A van linked to Sayoc has also emerged, showing heavy anti-Hillary stickers and pro-Trump stickers plastered all over its surface.
William Sweeney, assistant director in charge of the FBI's NY field office, said after Sayoc's arrest that he was "attempting to create an atmosphere of fear and intimidation from California to the eastern seaboard".
Sayoc initially indicated in court that although he packed the devices with fertilizer and powder from fireworks, he intended them only to look like pipe bombs, not to detonate.
Sayoc has been held without bail since his late-October arrest outside a South Florida auto parts store.
The first package was found on October 22, a Monday, and the investigation and anxiety only grew as more devices were identified in the days that followed.
The indictment said others targeted by the mailings received similarly marked pictures of themselves along with the explosives.
Prosecutors say evidence against Sayoc included DNA linking him to 10 of the explosive devices and fingerprints on two of them.