In September 2013, it was revealed that Oh had been dating T-ara member Soyeon for the past three years.

[7] On December 2, 2021, Oh announced through his social media that his wife is pregnant.

[8] On July 7, 2022, his wife gave birth to their first child, a daughter.

[10] He later debuted as a soloist in September 2006 with the album Issue under the stage name OJ.

[11] Oh was a cast member in the variety show Law of the Jungle in 2013 and 2014,[12] and appeared in MBC's King of Mask Singer in 2015, under the alias "Lonely Man Leon"[13] In August 2021, Oh signed with Bless Ent following the expiration of his contract with the former agency.