The actor announced the news in a post on his Facebook page.
"A little update for you: I just spend this last week shooting a guest star role on Gossip Girl," he said. "It's slated to air late March/early April. I'll keep you posted."
Gregory, who is best known for his role in One Life To Live, will be playing a friend of the real Charlotte Rhodes, who is also known as Lola, TV Line reports.
Ella Rae Pack recently made her debut as Lola.
Gossip Girl airs on Mondays at 8/7c on The CW.
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