The post was shared with her followers in order to encourage others to register to vote in honour of the infamous civil rights activist. Michelle turned 56 on Friday, and asked her followers on social media register with the When We All Vote organisation.
The organisation runs registration events up and down the country to ensure that as many Americans as possible are registered to vote.
Michelle launched the organisation in 2018 with co-chairs including actor Tom Hanks, singer Janelle Monae, composer Lin-Manuel Miranda, NBS star Chris Paul, singer Faith Hill and singer Tim McGraw.
She wrote on Twitter: “To honour Dr. King’s legacy, we all can play a role in ensuring our friends and family make their voices heard in every election.
“By sitting out, we’re allowing others to make decisions for us.”
The 2020 US election will take place on November 3.
As well as deciding who the US people want as their next President, there will be 35 congressional seats up for debate.
The Democratic Party currently holds the majority own the House.
But the Republican Party holds the majority in the Senate.
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But only around 157.6 million of those Americans said that they were registered to vote.
Michelle celebrated her birthday last week after she had a record-breaking year.
She managed to garner both Grammy and Oscar nominations.
And she bought a house with her husband Barack in Martha’s Vineyard.
She was also named the world’s most admired woman as well as one of PEOPLE’s “People of the Year.”
Before becoming First Lady, Michelle attended Princeton University and Harvard Law School.
She had a career as an attorney at a Chicago Law firm called Sidley & Austin, where she also met her husband Barack Obama.
She then worked at the Chicago mayor’s office, the University of Chicago and the University of Chicago Medical Centre.
Her best-selling memoir, ‘Becoming’, sold more copies than any other book published in the US in 2018.