In Gyo-jin is the eldest son of two siblings. His father, In Chi-hwan, is the CEO of Sungwon Industry, a plastic company that generates annual sales of 20 billion won in synthetic resin. His father always boasts about him because he always prioritizes his education and passion for his acting career. His brother, In Doo-jin, also works as an actor.
He spent his school time at Jochiwon Kyeodong Elementary School, Jochiwon Middle School, Bugil High School, and Dankook University. In the university, he pursued an English Language and Literature major.
In 2008, he was discharged for two years for military service. In June of the same year, he also announced that he was dating actress Seo Woo. The two met in the drama If Tomorrow Comes and became close friends while filming. They confirmed the news after getting caught together at a cafe in Hannam-Dong, Seoul. But, in May 2013, they broke up and decided to focus on their careers.
Then, in 2012, In Gyo-jin revealed that he was dating his longtime friend So Yi-hyun. They were in the same agency, Keyeast Entertainment, for 12 years and became co-stars in the dramas Fairy and Swindler (2013), Aeja’s Older Sister, Minja (2008), and Happy Ending (2012). After being friends for decades, they decided to date. Two months into dating, their relationship was announced to the public. Not long after their dating news broke out, they also announced they were getting married. The wedding took place at Raum, a wedding hall located in Yeoksam-dong, Southern Seoul, on October 4, 2014. In the press conference for their wedding, So Yi-hyun revealed her thoughts:
“I’ve known him for 14 years, so he’s more like my brother now. I see him more as my family than my lover.” She said.