Actors including Marvel star Chadwick Boseman have said they were inspired to join the Academy because of the #OscarsSoWhite diversity campaign.
"I felt obligated to join," said Boseman, who plays superhero Black Panther in two upcoming Marvel films.
Rita Wilson said it was the right time to join because the Academy was "open to hearing what the issues were".
The organisers of the Oscars intend to double the number of female and minority members by 2020.
'Be a voice'
The move follows complaints about the lack of ethnic diversity among this year's nominees. The Academy had been criticised over a lack of diversity amongst Oscar nominees, with no non-white nominees in the acting categories.
Boseman, speaking at an Oscars event in the US, added: "After a certain number of years when... you feel like there are worthy films that should be nominated or presented, yeah, you have to join.
"You have to be a voice."
Wilson, who recently appeared in My Big Fat Greek Wedding 2, said #OscarsSoWhite prompted her to join the Academy of Motion Picture Arts and Sciences. Her husband Tom Hanks has been active with the organisation for years.
"I have never been a member and I thought this is the right time," she told a reception for new members in West Hollywood, California, on Monday.
"It feels right because it seemed to me the Academy was really open to hearing what the issues were, not only with colour but with women and all sorts of diversity."
Academy president Cheryl Boone Isaacs told guests: "You are proof that the Academy is committed to, and working toward, its goal of inclusion."
Screenwriter Phyllis Nagy said she wants to "open up the diversity issue" now that she's an academy member.
"I think we have to address everything," the writer of Cate Blanchett film Carol said.
"It's not just Oscars so white. It's Oscars so male, Oscars so straight. Hopefully the new member initiative that the Academy announced will help."