Justin Montalvo was born on October 9, 1997 in Wilkes-Barre, Pennsylvania, where he was also raised along both parents and one brother. He gained passion for hip-hop around 2016. He would record his music at the time using an Xbox headphone set. He would be able to pursue his full-time music career with the help of rapper John Anthony, who would sign J Mont to his independent record label and later help release his debut professional studio album.

Justin Montalvo was born on October 9, 1997 in Wilkes-Barre, Pennsylvania, where he was also raised along both parents and one brother. He gained passion for hip-hop around 2016. He would record his music at the time using an Xbox headphone set. He would be able to pursue his full-time music career with the help of rapper John Anthony, who would sign J Mont to his independent record label and later help release his debut Currently signed to Villainous Records, J Mont became the first outside artist, besides John Anthony himself, to sign with the up-coming hip-hop label Villainous Records. He captured John Anthony's attention in late 2021, and was quickly signed to his label.

J Mont first gained exposer with the release his first solo single "The Kickoff (Freestyle)", which is a short freestyle verse track under two minutes, under Villainous Records. The song was mixed, mastered and produced by John Anthony. A month later, he would appear on John Anthony's studio album Villaination!, which was released on February 11, 2022. He would be featured on three songs, "Been That Real", "Midnight Cypher" and "Look At My Life", which has over 10,000 worldwide streams and has received its own music video shortly after the albums release.

Following off the early recognition, Villainous Records would announce J Mont's debut album. He would release "Bandz", which would be the first single from his debut album. On May 27, 2022, J Mont would release his debut album Premonition under Villainous Records. The album was compiled of ten songs and featured singer SoundingBlue, KaCe and rapper John Anthony, who was credited for mixing, mastered and produced the album. On September 24, 2022, the album received a commemorative silver record plaque for reaching over 5,000 worldwide streams the first two weeks. Later, one of the albums hit songs "Livin' This Life" released a music video in December of 2022. On October 7, 2022, J Mont released the single "Worst Way", featuring Vidal Garcia. The song was again mixed, mastered and produced by John Anthony and distributed by Villainous Records and Chaos Music Group.  On December 4, J Mont and Villainous Records agreed to a contract extension that would keep the emcee on the record label for three-years.

In 2023, J Mont released "Sleep Walking" on July 1. He would later release his second studio album Mont Rushmore, which released on August 11. On September 15, J Mont and rapper John Anthony released the single "Give It To Ya", which samples the 2009 song "Sugar" by Flo Rida. On October 1, Villainous Records announced Heroes 2 Villains, a collaborative album with John Anthony, which released on October 13. The album was announced via John Anthony's Instagram, however, a duo album between the two was surfaced around for the better part of 2023. John Anthony and J Mont's duo album Heroes 2 Villains released on October 13, 2023, and featured independent rappers such as Frizz, Tony Lonl3y and Phoenixx Rose, while a majority of the production was handled by several different producers. The album marked as the final album released under Chaos Music Group, the parental music management agency for Villainous Records. On December 8, John Anthony and J Mont performed at the Sherman Showcase at The Sherman Theater in Stroudsburg, Pennsylvania for their "Heroes 2 Villains Concert". The event also featured independent rapper Frizz as the shows opener.

To begin the 2024 year, J Mont released his first single, "Gassed Up" on April 5. Two weeks later, he held a featured preformance at The Keystone Stage in Olyphant, Pennsylvania on April 20. On May 24, J Mont would release his second single "The Valley". On December 27, he would release yet another single entitled "Told You" before heading into the new year. 

In 2025, J Mont released his forth single "Back 2 The Future", which features rapper John Anthony, on February 27. Two months later, he would go on to release his third studio album Alter Ego, which featured all four of his recently released singles. The album compiled 10 songs, with two features from John Anthony, along with independent Brooklyn rapper Jason Rose. Aside the abundance of singles on the project, the album formed yet another hit song with "Matter of Fact", which featured John Anthony. Seventh months later on November 21, the song released as a remix single, which also featured Jason Rose.

On March 28, J Mont was announced to preform yet again alongside John Anthony and Frizz for their third headlining show "The 3Peat Show", which was set for August 16. Two months before the showcase, Frizz was removed for the lineup due to personal reasons. The show continued with it's promotion until mid July, where then J Mont announced he will no longer be participating in the show due to an injury. With just under 30-days until the show, John Anthony retitled the show "Fuck It, I'll Do It Myself". 

As of December 5 of 2025, J Mont's contract with Villainous Records expired and was not re-signed, currently making the artist an unrestricted rapper.