The Oscar winner is no longer part of the Oscar club after the board of governors -- which includes Hollywood royalty like Steven Spielberg and Tom Hanks -- met at their headquarters in Beverly Hills Saturday and voted to expel him ... stripping away his lifetime membership.

The Academy issued a statement after the meeting, saying their decision was made to "send a message that the era of willful ignorance and shameful complicity in sexually predatory behavior and workplace harassment in our industry is over."

It continued ... "What's at issue here is a deeply troubling problem that has no place in our society. The Board continues to work to establish ethical standards of conduct that all Academy members will be expected to exemplify."

As we've reported ... Weinstein's been fired by his own company and is currently in Arizona for rehab.

He won an Oscar in 1999 for "Shakespeare in Love" and was nominated in 2003 for "Gangs of New York."