The league said last month it had found “continued misconduct” at most league clubs after an earlier investigation uncovered evidence of sexual harassment and abuse.
The NWSL investigation spent 14 months examining complaints from NWSL players and uncovered systemic failures by the league.
Coaches banned for life on Monday included Paul Riley, Christy Holly, Rory Dames and Richie Burke.
Former Portland Thorns coach Riley was prominent in a separate US Soccer investigation led by former US Attorney General Sally Yates.
Former Chicago Red Stars coach Dames also came under scrutiny in Yates’ report, which details allegations of verbal abuse and insults to players.
Holly, a former Racing Louisville coach, was fired after being accused of sexually coercing and groping a player.
Meanwhile, the Washington Spirit’s Burke was reported to have made comments about race and ethnicity.
Seven other people have also received suspensions or will be required to acknowledge wrongdoing and accept responsibility for misconduct before being considered for future NWSL employment.
Meanwhile, the NWSL said its own league office would be fined at least $1 million and required to undergo a sweeping overhaul.
NWSL Commissioner Jessica Berman said the league “will continue to prioritize the implementation and improvement of policies, programs and systems that put the health and safety of our players first.”
“Those actions are critical to the future of our league, especially as we build a league that strengthens our players’ ability to succeed and thrive on and off the field,” Berman added.
The Chicago Red Stars will be fined $1.5 million, the NWSL said, while the Portland Thorns would be forced to pay $1 million.