The 41-year-old actor, who was in the country to promote his upcoming film "Deadpool 2", wore a unicorn mask and a silver cape and sang the Annie classic "Tomorrow" on the show titled "King of Masked Singer".
In the video available on the verified MBCentertainment YouTube channel, Reynolds can be seen beginning the episode with his song. Both the judges along with the audience listened to the song in rapt attention, trying to ascertain the identity of the masked singer.
The Hollywood star, then, pulled the mask away and waved to the rising crazy screams and greater applause erupting from the audience members.
The judges too appeared shocked at the revelation.
"The unicorn, who gave us a special grand opening for today's stage, is Hollywood's star Ryan Reynolds."
The actor, who was accompanied by a translator, said in his wry sense of humour style, "Hello, everybody. I'm so sorry about that song..."
"Thank you guys for having me. This is such a thrill, this is an unbelievable honour for me. You guys pushed me to my limits and I thank you for that. That's just the best, thank you," he added.
When the host asked whether he was nervous about his performance, Reynolds said, "Yes, absolutely. I'm wearing an adult diaper."
He also quipped that he did not even tell "my wife" (Blake Lively) about his secret appearance on the South Korean show, which is best known for showcasing the hidden vocal talents of K-pop idols.
"Deadpool 2" releases this Friday.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)