[1] On December 26, 2012, Niel, alongside Beast's Yoseob, 2AM's Jo Kwon, MBLAQ's G.O, and Infinite's Woohyun formed a 5-member one-time unit named Dramatic Blue for their song, "Tearfully Beautiful", for SBS Gayo Daejeon's The Color of K-Pop.

[3] on January 27,at the program of Mnet's "4 Things Show" Niel released the self-produced track "Affogato", which would be included on his first solo album.

[5] His solo mini album oNiely which contains seven songs, was released on the same day and topped the Gaon chart.

[6][7] On May 15, 2015, Niel and other artists including Exo, Sistar and Ailee sang a KBS1's Special Program 'I Am Korea' theme song "The Day We Meet" for Gwangbok 70th Anniversary.

"[8] Niel released his second mini album Love Affair... January 16, 2017, containing seven songs, including the title track of the same name.