Mirror In 2018, Lau quit his reporting job to audition for
ViuTV's reality talent competition
Good Night Show - King Maker, and finished in top 20. While only the top 10 finalists were guaranteed a contract with
ViuTV, Jer managed to catch the attention of producer Ahfa Wong, who invited him to join the boy group
Mirror. Jer initially declined, but was ultimately convinced. The group debuted on 3 November 2018 with the single "In a Second" ().
Solo Activities Lau's debut single, the
soft rock ballad "Tale of Water Torture" () was released on 29 February 2020. "Tale of Water Torture" peaked at number three on the Ultimate 903 Chart, RTHK Chinese Pop Chart and number four on Metro Radio Pop Chart. His second single "Tale of Final Lucidity" (), released in August, achieved commercial success, peaking at number one on the Ultimate 903 Chart and ViuTV's Chill Club Chart. He is the eighth artist in history to have a number one single on the Ultimate 903 chart during his debut year. The release of "Tale of Wind Spirit" () in October capped off what was dubbed the Trilogy of Tales (). Lau again collaborated with singer-songwriter Ng Lam Fung and lyricist Siu Hak on his fourth solo single "A Madman's Diary" () released 17 March 2021. Lau remarked that "A Madman's Diary" is a tribute to legendary rock band
Queen and their song "
Bohemian Rhapsody", noting that he wanted to bring something unconventional into the Cantopop scene. The song is also the first of three songs forming the Rebirth Trilogy (). The
progressive rock single topped the Ultimate 903, the Chinese Pop Chart, and the Chill Club Chart. His fifth single, "Castle of Sand" () was released on 16 July 2021. On 18 August, it peaked at number one on the Ultimate 903 music chart. On 13 October, Lau released his seventh single "Stellar Moments of Humankind" (). The song takes the same Chinese title as the history book
Decisive Moments in History () by
Stefan Zweig. Produced by Carl Wong, the song serves as the conclusion to the Rebirth Trilogy. On 26 January 2022, Lau's single "MM7" was released to streaming platforms and radio stations. The song takes its title from a newly coined slang term "MM7" meaning awesome or fantastic (), which in turn originated from a typo committed by one of Lau's fans when typing the character using
Sucheng input method. "Rules of Parting" () was released on 20 April 2022, its music video being released three days later. This was followed by his tenth single "Steps to Self-Destruction" () on 11 July, and the eleventh single "Watching the Clouds Rise" () on 25 November. "Watching the Clouds Rise" charted number one on the Chill Club Chart in 2023, as such the single was nominated for Song of the Year at the Chill Club Awards 22/23. Lau held his first solo concert Across the Universe at the
Hong Kong Convention and Exhibition Centre from 7 to 10 July 2023. He released his first
LP I am the I on vinyl on 6 February 2024. A signing event was held on 24 February for 400 fans. == Acting career ==