Born in Seoul and raised in Ilsan, RM began his music career in the underground Korean hip-hop scene as a teenager, going by the name Runch Randa.

[B] RM has also collaborated with artists such as Warren G, Krizz Kaliko, MFBTY, Primary, Gaeko, Wale, Fall Out Boy, Younha, and Lil Nas X. Kim Nam-joon was born on September 12, 1994, in Sangdo-dong,[3] Dongjak District, Seoul, South Korea, and grew up in Ilsan District, Goyang, where his family moved when he was aged four or five.

In 2007, as a first-year middle school student, he began rapping in local amateur hip-hop circles, creating his first self-composed recording with the program Adobe Audition (then called Cool Edit) and later participating in his first concert in 2008.

[9] He formally changed his stage name to "RM" in November 2017, as he determined that "Rap Monster" was no longer representative of who he was or the music that he creates.

[9] However, following the audition, rapper Sleepy exchanged contact information with RM, whom he later mentioned to Big Hit Entertainment producer Pdogg.

[19] RM trained for three years with fellow rapper Min Yoon-gi and dancer Jung Ho-seok, later known as Suga and J-Hope, respectively.

[25] Through reality television show American Hustle Life, which was used to produce Dark & Wild,[26] RM formed a working relationship with Warren G, who offered to write BTS a beat.

[27] In an interview with Korean magazine Hip Hop Playa, Warren G stated that he had befriended BTS through the program and had kept in touch with the band after they returned to South Korea.

The program began airing on February 26, 2015; however, RM left the show after 22 episodes due to BTS' 2015 Red Bullet world tour.

[9] The following year, RM recalled that he had largely written about the negative emotions he had been carrying, such as anger and rage, but stated that the songs are not "100% under [his] sovereignty" and that he felt many parts of the mixtape were "immature".

[36] In September, he headlined hip-hop concert All Force One 2015 - Hot & Cool alongside Korean veteran rappers Paloalto and Verbal Jint.

[37] In August 2016, vocal duo Homme released a single titled "Dilemma", which was co-produced by RM and Bang Si-hyuk.

[57] This was followed by a feature on the track "Don't" by South Korean indie singer eAeon, from his second solo album released on April 30, 2021.

[59] Pursuant to an accompanying announcement that the band would be devoting more attention to individual endeavors going forward[60][61]—they went on an extended break from most group activities shortly afterwards[59]—he featured on the single "Sexy Nukim" by "alternative K-pop group" Balming Tiger in September,[62] and commercially released his debut solo studio album Indigo on December 2.

[63] Led by the single "Wild Flower", the album peaked at number three on the Billboard 200, making RM the highest-charting Korean solo artist in chart history at the time.

While there, in an interview with EFE—published in March—he reflected on the search for his own identity, after having followed the dictates of K-pop trends for the past 10 years as part of BTS, additionally revealing that he would "not be taking on any projects in the near future" in light of his approaching mandatory military service.

[74] In 2017, American hip-hop magazine XXL included him in its list of "10 Korean Rappers You Should Know", with writer Peter A. Berry stating that "Rap Monster rarely fails to live up to his name".

Berry described RM as "one of the region's most dexterous rappers, capable of switching flows effortlessly as he glides across an array of diverse instrumentals".

[75] Crystal Tai of the South China Morning Post noted that RM has "received much praise for his natural flow and lyrics".

Speaking about RM's work, Noisey's Bianca Mendez wrote that "he's got some My Beautiful Dark Twisted Fantasy [by Kanye West] in him, but he's closer to...Earl Sweatshirt and Chance the Rapper in spirit, and that's exciting".

[79] In July 2021, he and the members of BTS were appointed Special Presidential Envoy for Future Generations and Culture by President Moon Jae-in to help "lead the global agenda for future generations, such as sustainable growth" and "expand South Korea's diplomatic efforts and global standing" in the international community.

[80] On June 1, 2023, RM was appointed as the Public Relations Ambassador for South Korea's Ministry of National Defense Agency Remains Excavation and Investigation Team.

[81] RM underwent septoplasty for his nasal septum deviation in 2018 and temporarily withdrew from band activities while recovering from the operation.

[85][better source needed] For his 25th birthday, RM donated ₩100 million (US$85,810.58) to the Seoul Samsun School to help hearing-impaired students receive music education.

[90] On November 22, 2023, Big Hit announced through Weverse that RM, along with bandmates V, Jimin, and Jungkook, had started the enlistment process to carry out his mandatory military service.