Shila Iqbal, who only recently joined the Leeds-based soap as character Aiesha Richards, has been fired after the social media posts were discovered.
It is understood that Ms Iqbal was 19 at the time the tweets were posted back in 2013.
The actress is a recent cast member and only joined the series as a regular at the end of March.
-> Coronation Street star Liam Bairstow marks World Down Syndrome Day with 'follow your dreams' appealA spokeswoman for the soap today (Thursday) confirmed the news.
She said: "As a consequence of historic social media posts Shila Iqbal has left her role as Aiesha Richards on Emmerdale.
"The programme took the decision not to renew her contract as soon as these posts were brought to the company's attention."
Ms Iqbal has previously appeared in BBC's Citizen Khan, Lala's Ladies and the film Eaten By Lions.
She has since deleted her Twitter account.