Harpo Productions said 178 former Freedom Riders are set to appear on Wednesday's episode of "The Oprah Winfrey Show" in one of the largest Freedom Riders gatherings since 1961.
Winfrey said she owes "a deep debt of gratitude" to the Freedom Riders, adding that she knows her "life would be different were it not for them."
Guests on the episode are to include U.S. Rep. John Lewis of Georgia and John Seigenthaler, who was assistant to then-U.S. Attorney General Robert Kennedy. Both men were beaten during the civil rights movement.
The episode is to be among Winfrey's last. "The Oprah Winfrey Show" ends May 25 after 25 years.
The Associated Press contributed to this report.