Choi Won-jae (Korean: 최원재, born October 26, 1993), better known by his stage name Kid Milli (Korean: 키드밀리), is a South Korean rapper. He released his first extended play, Maiden Voyage, on February 23, 2017, and gained further recognition after finishing as the second runner-up in Show Me the Money Season 777.

Choi Won-jae was born on October 26, 1993 in Yeoui-dong, a neighborhood in the Yeongdeungpo district of Seoul, South Korea. His mother previously ran an entertainment company, which shut down after it went bankrupt. Choi's parents are divorced, and his two older sisters have passed away. One of his sisters died in a car accident, and another committed suicide. To support his mother, Choi began to work from a young age.

Choi graduated from Pungmu Middle School, and dropped out of Pungmu High School to become a rapper and make music. He attended an academy to study for the High School Diploma Qualification Exam, a Korean equivalent of the GED, and earned his diploma after passing the test.

Before becoming a rapper, Kid Milli was a StarCraft pro-gamer.

He was a mentor on High School Rapper Season 3.

He was also a mentor in Show me the Money Season 8.^{[citation needed]}