The French actress accused the Academy of Motion Picture Arts and Sciences of "insufferable hypocrisy" over its decision in May to expel her husband over his statutory rape conviction in the US.
The 84-year-old director is currently suing the Academy over the move.
The Academy announces a round of invitations every year and has been bolstering its ethnic and female representation in the light of criticism over its predominantly white, male membership.
"How can I pretend not to know that the Academy a few weeks ago kicked out my husband, Roman Polanski to satisfy the zeitgeist," Seigner said in an open letter published by France's Journal du Dimanche. "The same Academy that rewarded him with the Oscar for best director for The Pianist in 2003. Strange amnesia!"
She added that she was not so much of an "arriviste" to forget that she has been married to "one of the greatest directors" for 29 years.
1977 plea bargain
Polanski admitted the statutory rape of a 13-year-old girl in a plea deal in 1977.
A judge promised that the 48 days he spent in custody would be the only prison time he would serve.
But in 1978 he fled to France, apparently convinced the judge would back out on the deal.
He has since refused to return to the US without assurances that he would not serve additional time in prison.
Feminists in France have demonstrated outside events where he has been honoured and his case has gained renewed attention due to the #MeToo movement in reaction to the revelations about Hollywood moghul Harvey Weinstein.