Fashion King tells the story of young aspiring designers in Dongdaemun Market as they dream of success, and the relationships, love, and challenges they face along the way.Kang Young Gul has never had any goals or dreams for a bright future until he meets Lee Ga Young. Together they work towards their dreams.

This drama is set in Sungkyunkwan University during the Joseon era, revolving around the exploits and love stories of four youths. When her younger brother falls ill, Kim Yoon Hee enters the school in his place disguised as a boy in her desperation to find a way to support him, and becomes friends with Lee Sun Joon, extremely rich and the brains of the gang, playboy Goo Yong Ha and the rebellious Moon Jae Shin.

Kang Chil Woo is a lowly officer during the Joseon era. Chil Woo is not a very smart and one of his life long goals is to become a midlevel officer. However when night falls, he is no longer that low level officer but instead a top assassin in an assassination organization. He gives out punishment to criminals and gives justice where needed. So Yoon and Chil Woo have a tragic love story. Yeon Doo is the daughter of a fallen yangban who owns a textile shop. She falls in love with Chil Woo after he rescues her from thugs who were harassing her.

Cho Jae Hee is a man in his 40s who is very stubborn and hasn't gotten married yet. His personality is so unbearable that women don't find him attractable nor a good candidate for marriage. However, Jae Hee, is perfect in everything that he does. His life will be surrounded by three different women. Jang Moon Jung is a doctor that he meets one day, Jung Yoo Jin is his neighbor whom he meets due to a disturbance, and Yoon Ki Ran is his colleague at work.