The president said he would be signing a "full and complete pardon" later on Tuesday following the announcement.
"She was never pardoned, did you know that? What took so long?" Mr Trump said.
Ms Anthony, a women's suffrage leader, was known for pioneering the movement to give women the right to vote, but she was also vocal about being anti-slavery and pro-voting rights for all.
The pardon was announced on the 100-year anniversary of the ratification of the 19th Amendment, which prohibited voting discrimination on the basis of sex. The amendment is also known as the Susan B Anthony amendment.
In 1872, Ms Anthony was arrested in her hometown of Rochester, New York, after she convinced nearly 50 women in her town to register to vote for the presidential election. On Election Day, the pioneer showed up to a polling place with 14 other women and convinced the election inspectors to allow them to cast their ballot.
She was arrested and charged with voting illegally by a US Deputy Marshal in the weeks following the election. In a highly publicised trial, Ms Anthony was found guilty and ordered to pay $100 fine for voting. The activist declined to pay the fine, a move that could've landed her in jail until she paid, but instead the judge decided to not have her taken into custody.
Congress passed the 19th amendment in 1919, and it was ratified on 18 August 1920.
Although Ms Anthony was not alive to see the women earning the right to vote, she has remained a prominent figure in the 19th amendment coming to fruition. Her gravestone located in Rochester remains a prominent spot for people to visit around the election. In 2018, many women placed their "I voted" stickers on the stone to honour the pioneer.
Mr Trump's pardon comes as Republicans and Democrats have faced off in recent weeks about voter fraud and what the upcoming election might look like amid the coronavirus pandemic. Democrats have accused the president of attempting to undermine the election by interfering with the United States Postal Service (USPS) and its ability to transport mail-in ballots.
The president has denied these accusations but said remained firm on his perspective that the upcoming election will be "rigged" if voters are universally allowed to vote by mail.
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