Born in Seoul on 16 June 1993, Park is the youngest of three siblings. "Bo-gum" (寶劍) means 'precious sword'. His mother died when he was in fourth grade. He started learning to play the piano when he was in kindergarten and was a pianist and choir member at church. He was also in the swimming varsity team of Seoul Mokdong Middle School. During Park's sophomore year of high school he sent a video of himself singing and playing the piano to prominent talent management agencies which led to several offers. Park, who initially wanted to be a singer-songwriter, later changed his career path after a suggestion that he would do well acting. He graduated from Shinmok High School in 2012, and enrolled at Myongji University as a Musical Theater undergraduate in March 2014. The following year, he represented his university's cultural overseas exchange program where he traveled to cities in England, France, Italy and Switzerland.