"Later today, I will be signing a full and complete pardon for Susan B. Anthony. She was never pardoned. Did you know that? She was never pardoned," the president said, calling the move "fantastic."
Trump made the announcement alongside first lady Melania Trump, wearing white, at a White House event commemorating the 100th anniversary of the ratification of the 19th Amendment -- which ensured women the right to vote. It was ratified on Aug. 18, 1920, 14 years after Anthony died.
"She was guilty for voting. And we are going to be signing a full and complete pardon," Trump said.
Although he didn't say so specifically, the symbolic gesture appeared aimed, at least in part, at female voters Trump is looking to court ahead of the election -- as polls show the demographic currently prefers former Vice President Joe Biden.
It also comes amid Trump's relentless claims, without evidence, of widespread fraud if there is universal mail-in voting in November's election, and mounting concern over United States Postal Service disruptions that Democrats argue endanger the voting rights of millions of Americans planning to vote by mail due to the pandemic.
While Trump -- who calls himself the "law and order" president -- has amplified fears of illegal voting heading into the 2020 election, the irony is not lost on some that Anthony was arrested for just that.
In a widely publicized trial in 1873, Anthony protested what she called "high-handed outrage upon my citizen's rights" and said she would "never pay a dollar of your unjust penalty." She never did, and the authorities declined to take further action.
"We have to have honest voting," Trump said at the same event Tuesday, continuing his attacks on mail-in voting. "That's what this is all about here. We have to have honest voting."
The president first teased on Monday he would pardon a "very, very important" person, only adding at the time it would not be leaker Edward Snowden or Michael Flynn, his former national security adviser.
Anthony does not fit the typical model for a Trump pardon, usually reserved to those he personally knows.
Most recently, Trump recently granted a controversial clemency to his longtime political adviser Roger Stone, who was convicted on several charges related to Russian interference in the 2016 election, including lying to federal officials.
Notably, she has faced criticism in recent years as some argue she sidelined Black women in the suffrage movement.
Anthony's pardon was welcomed by at least one group in her name, Susan B. Anthony List, represented at Tuesday's White House ceremony. The influential conservative organization raises money for anti-abortion political candidates.
"We are deeply moved and grateful to President Trump for honoring the legacy of this great American hero and we pledge never to tire in carrying on her unfinished work," the organization said in a statement.
Its abortion rights alternative, Emily's List, said in a tweet commemorating the 100th anniversary of the 19th Amendment, "As we recognize this milestone, we must also recognize the many women who were left behind."
ABC News' Jordyn Phelps contributed to this report.
This report was featured in the Wednesday, Aug. 19, 2020, episode of “Start Here,” ABC News’ daily news podcast.
"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.