Xenith announced Friday that the company terminated its endorsement deal with Brown.
"Xenith has decided to end our relationship with Antonio Brown," the statement said. "We look forward to seeing the Xenith Shadow worn by football athletes at all levels of play this fall."
After Brown lost two grievances to wear his preferred Schutt Air Advantage helmet model, which was outdated and no longer certified for use by the league, Xenith announced a partnership with Brown on Sept. 4.
Brown was expected to wear the Xenith Shadow during this season. However, the Patriots pass-catcher was seen on the practice field Wednesday wearing an approved Schutt Air XP helmet model.
Brown, who recently joined the Patriots after his release from the Oakland Raiders, was accused of sexual assault in three separate incidents, according to a civil lawsuit filed Tuesday in the Southern District of Florida.
The Patriots said they are aware of the lawsuit and take the allegations "very seriously." Brown denies the claims and is pursuing multiple legal options. The NFL is investigating the matter.