Aside from his group's activities, Yook has acted in television dramas Reply 1994 (2013), Plus Nine Boys (2014), Who Are You: School 2015 (2015), The Village: Achiara's Secret (2015), Guardian: The Lonely and Great God (2016), Mystic Pop-up Bar (2020) and The Golden Spoon (2022).

[5][6] His grandfather was the first to introduce red carp in South Korea, while his grandmother operated a fishing farm in Paju.

[12] On March 6, 2011, Yook also participated in the stage performance of "2011 CUBE Stars Party" with bandmate Seo Eunkwang, Im Hyun-sik, Jung Il-hoon, and supposed to be member Lee Min-woo.

[13] Yook entered the JYP 6th Audition Final Round before joining his current agency, Cube Entertainment.

[15][16] On March 23, 2012, Yook co-host SBS MTV's music program The Show alongside bandmate Lee Min-hyuk.

[30] Yook achieved his breakthrough when he landed a leading role in the teen drama Who Are You: School 2015, alongside Kim So-hyun and Nam Joo-hyuk.

[38] In 2015, Yook joined King of Mask Singer, competing under the alias Tired Bumblebee, and received good feedback for his performance.

[41][42] The couple went on to release a duet titled "Young Love", with the pair contributing to the lyric composition of the song with the help of his bandmate BTOB's Im Hyun-sik as the producer.

[62][63] In 2018, Yook held his first fan meeting, Paradise at TICC in Taiwan on February 11,[64] Macpherson Stadium in Hong Kong on May 19,[65] and in Manila, Philippines on July 13.

[68] It was revealed that he planned and made his close same-aged 95s friends, former Boyfriend members Youngmin, Kwangmin and Minwoo, Teen Top's Ricky and model Baek Kyung Do to have a variety show.

[74] The project concluded on February 6, 2020, with the first collaboration song between Yook and Ilhoon "HMHN" and "Hypnotized" which was performed with Peniel at 2018 BtoB Time - This Is Us concert.

[75][76] After a three-year acting hiatus, Yook made a return to the small-screen as part of the main cast of Mystic Pop-up Bar, a JTBC drama based on a popular webtoon of the same name in early 2020.

[77][78] On February 18, Yook left the cast of Master in the House after two years on the show prior to his mandatory military service.

[83] On December 22, iWill Media, a production company, announced that Yook has signed an exclusive contract as its first managed actor.

[90][91] After taking his final military leave in October 2021, Yook announced that he would not return to his unit following the army's protocols regarding the COVID-19 pandemic.

[93] In 2015, Yook took part in a fundraiser that auction items to the Social Welfare Community Fund for Love to support low-income children.

[94] In December, 2015, SBS revealed that Yook donated ₩3 million to Jeonbuk National University Hospital, which was the filming location of The Village: Achiara's Secret.