[1] He studied abroad in the United States, China, and Singapore and has lived outside of South Korea for a total of 11 years.

[3][4] In 2014, Hongseok joined YG Entertainment and participated in the reality survival program Mix & Match as a member of TEAM B.

He was eliminated in final episode alongside Jung Jin-hyeong, failing to debut as a member of iKON.

[11] In November 2017, Hongseok made his acting debut in the movie The Love That's Left  [ko].

In September, he was cast in the variety program Real Man 300, which featured celebrities experiencing life in the military.

[23] From January to March 2021, Hongseok starred as the supporting character Shin A-jun in the SBS drama Phoenix 2020.

[32] On April 1, 2022, the agency announced that Hongseok would be enlisting for his mandatory military service as an active duty soldier on May 3.

[33] On December 26, 2022, it was confirmed by the agency that Hongseok would be discharged from military service early due to depression and panic disorder with public phobia.

The event raised 42 million won, and all proceeds went to build the first Lou Gehrig's Nursing Hospital in South Korea.