"Today I've issued an executive grant of clemency, a full pardon, posthumously, to John Arthur 'Jack' Johnson ... The first African-American heavyweight champion of the world, a truly great fighter. Had a tough life," Trump said.
Johnson was convicted in 1913 of traveling with his white girlfriend across state lines, which was prohibited under the Mann Act -- also known as the White-Slave Traffic Act. The law, which hadn't yet gone into affect at the time of his conviction, was designed to prevent prostitution and "immorality" but was often exploited to intimidate interracial couples.
Johnson skipped bail and fled the United States after his conviction and later returned to serve a one-year sentence. He died in 1946.
Trump welcomed Johnson's family, current heavyweight champion Deontay Wilder and actor Sylvester Stallone to the event at the White House on Thursday. Stallone, who played the title character in the 1976 Oscar-winning boxing film Rocky, reached out to the president earlier this year to plead Johnson's case.
"I believe that Jack Johnson is a very worthy person to receive a full pardon, and in this case, a posthumous pardon," Trump said. "So I am taking this very righteous step, I believe, to correct a wrong that occurred in our history and to honor a truly legendary boxing champion."
Trump first floated the idea of granting the pardon earlier this year.
In 2016, the two senators, joined by Reps. Peter King, R-N.Y., and Gregory Meeks, D-N.Y., petitioned the Obama administration to grant the pardon. The bipartisan lawmakers sent a letter to the White House asking for the pardon in honor of the 70th anniversary of the Johnson's death.
The House and Senate previously passed resolutions to posthumously pardon Johnson, but no president has granted one until now.