The brand made the announcement Thursday in a tweet, welcoming Nyong'o to the Lancome family.
Nyong'o later said she felt "honored" to be joining "such a prestigious" brand that she had "always loved."
"I am particularly proud to represent its unique vision for women and the idea that beauty should not be dictated, but should instead be an expression of a woman's freedom to be herself," the actress said in a statement.
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