Jun was introduced as the newest addition to the South Korean boy group U-KISS in May 2014. In 2017, he joined and topped the male division of the KBS2 survival program The Unit: Idol Rebooting Project, which subsequently led him to debut in the project group UNB. In early 2019, he launched a solo career in Japan with the single album Phenomenal World. This was followed by the release of the single album Gallery later in 2019 to mark his solo debut in his home country.

Jun landed his first acting role in the 2017 tvN drama Buam-dong Revenge Social Club. In 2018, he starred in MBC’s Goodbye to Goodbye, which won him Best New Actor at the MBC Drama Awards. In 2020, he became part of the hit SBS action comedy series Good Casting, which earned him a Best New Actor nomination at the SBS Drama Awards. In 2021, he was nominated for an Excellence Award at the SBS Drama Awards for his work in the musical series Let Me Be Your Knight. That same year, he co-established the talent agency called Jflex.

In 2021, it was revealed that Jun helped the police apprehend a drunk driver, whom he spotted on his way home.