Noah tested positive for a prohibited over-the-counter supplement, according to the report.
Noah, who signed a four-year, $72 million contract prior to this season, has not played since February 4 because of a knee injury. The Knicks only have 10 games remaining in the regular season, so Noah's suspension will carry into the 2017-18 season regardless of when it starts.
The struggling Knicks (27-45) are well outside playoff contention and face the San Antonio Spurs, with the NBA's second best record, next.
The players' union believes the 6-foot-11 player made an unintentional mistake.
Noah is in the first year of a four-year, $72 million contract.
"After a thorough investigation, the NBPA believes that Joakim Noah did not intentionally or knowingly violate any policy", a union statement said. Noah did say if he could play he hoped to return this season, to begin the process of proving himself in NY. Noah has performed well below expectations, missing time throughout the season because of a hamstring injury. Signed over from the Chicago Bulls, Noah was averaging 5.0 points and 8.8 rebounds before his season ended.
Yahoo! Sports' The Vertical first reported that Noah would be suspended.