Jung Jae-won, better known by his stage name ONE, is a South Korean rapper, singer, songwriter, and actor.

ONE started his musical career as part of the hip-hop duo named 1Punch with Samuel under a collaboration between D-Business Entertainment and Brave Entertainment. They debuted on January 23 with the release of "Turn Me Back", which is the title track of their album The Anthem. On September 21, it was reported that YG Entertainment had scouted ONE. The exclusive contract with YG Entertainment came about after his participation in the fourth series of Show Me the Money. He was a member of "Team Zipal" under team leaders Zico and Paloalto until his elimination in the sixth episode. A year later, he returned and participated in the fifth series of the show. This time, he was a member of the AOMG Team under the leadership of Simon Dominic and Gray. He placed tenth in the season.

In 2016, he also made appearances in the music videos for MOBB's "Hit Me" and Lee Hi's "My Star".
On July 11, ONE officially debuted as a solo artist under YG Entertainment with the release of his first EP, One Day. It was also reported that he became the first male solo artist to debut from YG Entertainment in 14 years since Se7en's debut in 2003.

In October, YG Entertainment announced that One would start his acting career with a supporting role in tvN's drama A Korean Odyssey that was aired in December. In November, One was cast in a romantic one-act drama Anthology together with Shin Eun-soo. He played a smart and good looking country boy with a hidden secret.

In February, it was confirmed that One and Soyou were to join Channel A's Heart Signal season 2 as new panelists.

In July 2018, One was confirmed to make his big screen debut with the romance film Goodbye Summer alongside Kim Bo-ra where his character was a high-school student who is terminally ill. In August, he was cast in the tvN drama Room No. 9. The same year, he was cast in the historical drama Asadal Chronicles as the younger version of Jang Dong-gun's character.