The news comes after Brown was accused of sexual assault in a civil lawsuit filed by former trainer Britney Taylor in Florida.
"Antonio Brown is not a Nike athlete," the spokesperson told Michael Silverman of the Boston Globe. Further details about the company's decision were not provided.
Helmet manufacturer Xenith ended its partnership with Brown last week, per ESPN's Adam Schefter.
Drew Rosenhaus, Brown's agent, said during an appearance on ESPN's SportsCenter (via Frank Schwab of Yahoo Sports) on Sept. 11 that his client denies the allegations.
"Antonio will be cleared," Rosenhaus said. "These allegations in the lawsuit are false. They are not true. They are absolutely untrue."
He added: "In no way do we condone any type of illegal conduct, misbehavior. None of this happened here. This is a money grab. I'll repeat this: This is a money grab. In my opinion, this is a money grab."
A second woman alleged Brown behaved inappropriately toward her while she was painting a mural in his home in 2017. She detailed an encounter with the then-Pittsburgh Steelers wide receiver to Robert Klemko of Sports Illustrated:
"I was about 40 percent done on the second day, and I'm on my knees painting the bottom, and he walks up to me butt-ass naked, with a hand cloth covering his [penis] and starts having a conversation with me. Unfortunately, I've been tried [by men] a lot of times, so I just kept my cool and kept painting. After that, it all ended abruptly."
Brown's attorney, Darren Heitner, provided a statement to TMZ Sports: "Antonio Brown has reviewed the sexual misconduct allegations made by an unnamed artist included in a recently published Sports Illustrated article and denies that he ever engaged in such activities. There will be no further comment at this time."
The 31-year-old Miami native was traded from the Steelers to the Oakland Raiders in March. He was released by the Raiders in early September after fractures quickly developed in his relationships with general manager Mike Mayock and head coach Jon Gruden.
He signed with the Patriots following his release from Oakland and made his team debut Sunday, catching four passes for 56 yards and a touchdown in a win over the Miami Dolphins.
The NFL is investigating the allegations against him.