Harper, who has terminal brain cancer, will join Mary Tyler Moore and Cloris Leachman as guests on an episode of TV Land's Hot In Cleveland, which stars other Mary Tyler Moore Show alums Betty White and Georgia Engel, PEOPLE has confirmed.
A source tells PEOPLE: "The cast is really excited to have Valerie guest star. They feel she is a true icon, and they are touched by her story."
The episode will tape April 5, and the plot will center on another reunion – the five ladies decide to get their bowling team, GLOB: The Gorgeous Ladies of Bowling, back together, according to Deadline.com, which first reported the news.
The five women have not acted together in front of a camera since taping the Mary Tyler Moore finale in 1977. TV Land is not commenting on the reunion.
Moore, 76, has guest starred on Hot in Cleveland before, back in the second season. The show begins its fifth season on June 19.
Harper, 73, has been given a devastating diagnosis of leptomeningeal carcinomatosis. Her doctors say she has as little as three months to live.
Reporting by DAHVI SHIRA