It is a coming-of-age story and youth romance set during 19th-century Joseon Dynasty based on the web novel Moonlight Drawn by Clouds [ko] which was first serialized on Naver in 2013[1] and consequently published as a five-part series of books in 2015.

[8] The series is a coming-of-age story about Crown Prince Lee Yeong's (Park Bo-gum) growth from a boy into a revered monarch, and his unlikely relationship with eunuch Hong Ra-on (Kim Yoo-jung).

Chief producer Kang Byung-taek declined saying that the framework of the story had already been laid out and it would only yield complications with the cast and crew's respective schedules.

[18] The drama's first teaser, with lead actor Park dressed in dragon robe dancing to Jessy Matador's French pop song "Bomba" in front of Gwanghwamun, was released in July 2016 and became a viral hit.

[19][20] In a press conference held on August 18, 2016, director Kim Seong-yoon indicated that despite the series being set in the 19th century, the production aimed to show a more contemporary message adding: "Our focus was on creating a romance that's pretty and charming but also sad.

[26][27] The two-disc soundtrack album was released on October 27, 2016, and consists of 13 tracks including a humming version of "Because I Miss You", 13 instrumentals and three special background music created by folk-fusion band Second Moon.

[48] Both KakaoTalk and LINE released Moonlight digital stickers and three of Raon's outfits were made available for purchase in mobile game "I Love Nicky".

[66] In partnership with Viki, the series screened at University of California, Berkeley in October 2016 as a joint project of the campus' Korea-centric organizations, KUNA and K-Popular.