He passed the audition and was accepted into Woollim with a cover of Stevie Wonder's "Lately" and began training as an idol trainee.

Nam began his career as a model for a shopping mall alongside Beast's Junhyung and T-ara's Jiyeon.

Nam made his first foray into acting in August with a minor role in the drama The Thousandth Man.

[9] In February 2013, he released a duet song titled "Cactus" (선인장) with South Korean Indie Singer, Lucia.

[11] On February 20, 2014, SM Entertainment announced the formation of a special unit, Toheart, consisting of Nam and Shinee's Key.

School: Love On alongside Kim Sae-ron and group mate Lee Sung-yeol, playing the character Shin Woo-hyun.

[20] Nam currently plays as a striker for the South Korean celebrity football club, FC MEN.

[28] Nam appeared in the musical Barnum: The Greatest Showman, in Seoul, South Korea from August to October 2018.

[33] Nam held his first solo concert Arbor Day from November 2–4, 2018 at the Hannam-dong Blue Square,[34] with all the tickets selling out in two minutes.

Nam starred in the musical The Days at Bluesquare Interpark Hall in Seoul from February 22 – May 6, 2019, as Kang Moo-young, a presidential bodyguard who went missing 20 years ago along with a mysterious female companion.

[47][48] In early 2023, Nam was diagnosed with a rare form of cancer, which threatened both his participation in the already-planned Infinite comeback as well as his career at all as a singer and performer.