[15] NBC Universal joined the investors on September 15, covering half of the budget of ₩15 billion and raising the expectations for the drama,[16] which would have been filmed entirely before the broadcast and would be aired simultaneously in China and abroad.

[37][38][39] The jewels were all created by Jung Jae-in of Minhwi Art Jewelry, and IU herself designed the hairpin with the peony gifted by Wang So to the female lead.

[59] Moon Lovers: Scarlet Heart Ryeo was chosen as the most anticipated series of the second half of 2016 in China,[60] reaching 300 million views after the first three episodes on the online streaming platform Youku.

[71] The next episode previews released through Naver TV cast, South Korea's largest portal site, reached more than one million views each in early October.

[69] After the premiere, audience reviews were mixed, with the adaptation, the soundtrack, the photography, and Lee Joon-gi's acting being praised, while Byun Baek-hyun's performances received criticism.

[75][76][77][78] While for Kim Yoo-jin of TenAsia the drama's brevity (20 episodes against the 35 of the Chinese version) and the rapid pace weren't sufficient to introduce each character,[79] for MediaUs the first two episodes were interesting because they had made a good connection between characters through rapid development,[80] suggesting however that, if Moon Lovers had focused on the power struggles of the early Goryeo Dynasty "instead of setting up the Goryeo version of Boys Over Flowers," it would have been possible to receive a positive response from male viewers interested in political dramas.

"[79] With the 10th episode, the mood of the drama changed with the beginning of the power struggle over the throne among the princes, and the development of a three-dimensionality in characters considered "flat and dull" until that moment: Yonhap News again wrote that "IU has shed her comic acting and grasped Hae Soo's emotions in front of a tragic fate.

"[82] Lee Seung-rok of MyDaily also noted that after turning to tragedy in the second half, the acting, directing and writing had found stability, contributing to the increase in ratings.

[84][85] On the drama in general, Lee Woong of Yonhap News expressed a positive opinion, writing that Moon Lovers faithfully portrayed the tragedy of a love, tragic "not because of misunderstanding, jealousy, or selfishness", but because "one day, the ideals it's chasing have to be broken in front of reality.

[91][92] Due to Moon Lovers, Lee Joon-gi's popularity grew and the actor's name consistently topped the real-time and weekly portal sites search rankings.

[8][9][10] What was pointed out as the main cause of low viewership ratings, however, was the pre-production of the drama, which made it impossible to make changes on the way based on feedback, because filming had already ended.

[109][110] The network tried to remedy the problem by modifying the episodes starting from the sixth, adding new scenes and removing others, thus creating a version of the drama different from the one previously sold abroad.

[80] For Hankook Ilbo, the audience was tired of bad guys and complicated emotions, preferring instead a kind male lead and a simple story like in Love in the Moonlight, another historical drama of different content aired simultaneously on KBS2.