Anecdotes

He started to use the stage name Yoo Ah-In when making his debut in a TV commercial. His first management wanted to create a pretty stage name for him that fitted an idol image because his name Uhm Hong-Shik was considered too heavy, old-fashioned, and not refreshing sound for celebrity name. So his manager encouraged him to change his name, and he chose the name Yoo Ah-In. The 'Ah-In' part was taken from German word 'ein', means 'one', which implies he is a unique being.

Was discovered by a casting agent on the streets in front of his school when he was in his first year of high school. He came up to Seoul by himself and became independent. Before long he dropped out of school to carry on his acting career.

Attended Gyeongbuk Arts High School, majored in painting.

He created a fund for adolescents who have been discharged from welfare facilities. His fans join in making regular donations to the fund.

He has two elder sisters.

For his performance as Jongsu in Burning (2018), He became the first Asian actor to be included in The New York Times list of best actors.

As of 2020, his favorite character he played is Lee Sun-jae of Milhwe (2014).

Wrote an article about Closer, entre adultes consentants (2004) entitled "I also want to ask about love" that appeared in issue 605 of Cine21 magazine. [May 2007].

He wrote poems that he published in his personal blog between 2006 to 2011. In 2011, he contributed several essays related to the film Wan-deuk-i (2011), and in 2013, he published a series of columns in Dazed Korea for six months. From 2014 to 2016, he served the editor-in-chief of Tom Paper.

Adopted two Sphynx cats called Dobi and Jangbi in 2018.

Revealed that he experienced near-death car accidents twice. He got a driver's license in 2012.

In 2014, he launched a contemporary art gallery Studio Concrete with his fellow artist crew. He also acts as representative and art director for Studio Concrete.

Was scouted to be an aspiring idol and trained to sing.

He doesn't have religion.

Has stage fright.

Likes the expression of Tilda Swinton at the end of the film Amore (2009).

Likes to cook for his acquaintances.

Grew up in Daegu and Gumi and uses the Yeongnam dialect of Korean, but has rarely used in public.

Good friends with actress Jung Yu-mi and DJ Peggy Gou.