Debut with Day6 and first solo activities (2015–2018) Park debuted on September 7, 2015, as a vocalist and electric guitarist of JYP's first rock band, Day6. The band debuted with their first extended play
The Day, with the lead single "
Congratulations". On June 28, 2016, Park became an MC of
Arirang's
After School Club, a televised music talk show, alongside
Jimin Park, labelmate under JYP Entertainment, and
Kevin Woo, formerly of
U-KISS. He officially graduated as an MC of ASC on July 17, 2018. In 2017, Park opened his YouTube channel with the name JaeSix and published his first video on September 6, 2017. Over the next year, he uploaded videos of behind-the-scenes vlogs with Day6, as well as videos of activities with his friends. His "season one finale" was posted on July 6, 2018. A singular video was posted as part of "season 1.5" on October 10, 2018, marking the final JaeSix upload.
Rebranding to begin solo music career (2020–2021) Under the name eaJ, Park began a personal music project in 2020, called the eaJ Project, releasing self-written solo tracks. The first song, titled "LA TRAINS", was released on January 16, 2020 on SoundCloud and YouTube. With the start of his music project, he also made private all his previously published YouTube videos for JaeSix. His fourth song of the project, "Pinocchio", was later made private on his YouTube channel after the end of 2021. The fifth song, "Rose", was the only song to have a teaser clip posted before its release. He released eight songs through the eaJ Project, with the final song of the project, "Pacman", being released on July 5, 2020. On February 5, 2020, Park started his first podcast "How Did I Get Here?", abbreviated as HDIGH, as Jae of Day6, with Dive Studios. After over a year of activity, episode #70, the last episode, was released on June 2, 2021. On May 10, 2020, Park's activities with Day6 were placed on hold as the group took a hiatus to focus on their health, the day before their sixth extended play
The Book of Us: The Demon, with the lead single "Zombie", was released on May 11, 2020. During 2020, Park began streaming on
Twitch, becoming acquainted with
OfflineTV and Friends. He created his own clothing line called "From Friends" with Represent. On September 16, 2020, Park announced his first collaboration, with
Seori for "It Just Is", released on YouTube on September 22. The song also featured
Keshi contributing on production with guitar. The video animation was done by the artist Deisa. On September 21, 2020, Park and
2PM's
Nichkhun took on roles as members of crime-fighting boyband "4 2 Sing" in season three of
Big Hero 6: The Series. Park played twins Kwang-Sun and Ye Joon, one half of the boy band "4 2 Sing". On November 27, 2020,
DPR Live featured
Crush and Park on the single "Jam & Butterfly". On December 3, 2020, Park and
Keshi released their collaboration single titled "pillows" on YouTube. On April 19, 2021, after the group's hiatus for their health, Day6, including Park, released their seventh extended play
The Book of Us: Negentropy, with the lead single "You Make Me". The group did no promotions for the album. This was the last Day6 release to feature Park. Park was featured on Seori's single "Dive with You", released on August 22, 2021. Park performed at
Head in the Clouds Festival 2021 on November 6 to 7, 2021 at the Brookside at the
Rose Bowl in
Pasadena, California.
Departure from Day6 and official solo debut (2021–present) On December 31, 2021, Park announced via Twitter that he would be taking a hiatus from his promotions after 6 years as a member of Day6. The same day, JYP Entertainment announced that Park would be leaving the band and ending his exclusive contract with the company for personal reasons. On April 8, 2022, Park released a single titled "Car Crash" on music streaming platforms, starring gaming streamers
Valkyrae and
Kyedae from
100 Thieves in its music video directed by John Lee. This release marked his official solo debut. On April 11, 2022, Park released the music video for the song "Sincerely," on YouTube. "Sincerely," was later included on his second EP,
Smiling in Insomnia, in April 2023. On May 25, 2022, Park released his second "Mindset Collection" through the platform Dive Studios. Park performed at
Head in the Clouds Festival 2022 on August 20 to 21, 2022 at Brookside at the
Rose Bowl in
Pasadena, California. On October 28, Park performed as a guest artist at the MAX - North America Tour 2022 show at The Wiltern in
Los Angeles, California. For the first time in his solo career, Park performed as a headliner artist at
Head in the Clouds Festival 2022, which took place at Community Park PIK2 in
Jakarta, Indonesia on December 3 to 4, 2022. In December 2022, Park embarked on his first Asia Tour with 2 shows: one at Clapper Studio in
Taipei, Taiwan on December 6, 2022 and another at Gateway Theatre in
Singapore on December 8, 2022. On December 8, 2022, Park released a single, "Typical Story", on streaming platforms. The song was later included on his debut EP,
Laughing in Insomnia in February. Park performed as a headliner artist at
Head in the Clouds Festival 2022, which took place at SM Festival Grounds Parañaque City in
Manila, Philippines on December 9 to 10, 2022. On February 3, 2023, Park released his first EP,
Laughing in Insomnia, on streaming platforms, including the single "Typical Story", previously released in December. He also published a visualizer for the second track, "Sober Go Away", on YouTube on the release day. Shortly after, Park released his second EP,
Smiling in Insomnia, on April 21, 2023. Park's third EP,
Medicated Insomnia, was released on June 30, 2023. It included the pre-release single, "In My Civic", as well as releasing for the first time on streaming platforms three of the songs that had previously been released in 2020 as part of the eaJ Project: "LA Trains", "50 Proof", and "Pacman", with the titles of "LA Trains" and "Pacman" being re-stylized in lowercase. It also included the song "Sincerely,", which he had previously released on YouTube a year ago in April 2022. Park was featured on Vaultboy's single "Everything, Everywhere", released on November 3, 2023. On January 17, 2024, Park worked with Zaya Lyn to release a "Ghibli inspired version" of his song "Castle in the Sky", originally released in February 2023 on his first EP
Laughing in Insomnia. The single also included an instrumental version. Park released the single "Mad" on February 23, 2024. He released the single "Friendly Fire" on May 10 and released a visualizer for the song on May 24. Park and
Hindia collaborated for the single "Right Where You Left Me", released on July 5, 2024, with its accompanying visualizer. On September 1, 2024, Park embarked on his first world tour
when the rain stopped following me featuring cities in Asia and North America. He concurrently served as an opening act for part of the North American
Imagine Dragons's
Loom World Tour. In 2025, Park collaborated with the
Pinoy pop girl group
Bini for the single "Secrets", which was released on February 27 as part of Bini's EP
Biniverse. He would perform the song with BINI song during the Los Angeles leg of the
Biniverse World Tour 2025. == Personal life ==