Mainly a hip hop artist, his songs and performances often include influences of electronic music, such as drum and bass, hardstyle, and gabber.

Having qualified in second place from the second semi-final, he was scheduled to perform fifth in the final, but was disqualified from the competition amidst allegations of misconduct.

[4] The allegations were investigated by Swedish prosecutors, who dropped the case in August 2024 after concluding that they could not prove any criminal conduct.

[5] Joost Klein was born on 10 November 1997 in Leeuwarden, Netherlands,[6][7] and grew up in the nearby village of Britsum.

On 3 August 2018, Klein released the studio album M van Marketing [nl] together with Dutch rapper Donnie.

[13] To promote his studio album of the same title, Klein organised the Het gaat niet zo goed (transl.

The following summer, Klein performed at major Benelux festivals such as Pukkelpop, Pinkpop, Lowlands, and Zwarte Cross.

[17] According to a statement released by Klein's management, "Jackass" was recorded prior to the Russian invasion of Ukraine, and the collaboration with the Russian Village Boys was done after the group had left their homeland following the invasion, noting that "it has absolutely no bearing on what terrible things are still happening there, and is not pro-Russian".

[18] Klein released his eighth studio album on 13 September 2022, titled Fryslân after his home province of Friesland.

[19] In 2023, Klein scored his first hit in Germany with the single "Friesenjung", a collaboration with German rapper Ski Aggu and an adaptation of a song by East Frisian comedian Otto Waalkes.

[20] That same year, Klein expressed his interest in representing the Netherlands in the Eurovision Song Contest 2024 in Malmö, Sweden.

[26][24] The details of the altercation are unclear, but the Swedish police said it would be investigating whether criminal threats were made, not whether an assault occurred.

[29] On 12 August, the Swedish Prosecution Authority announced that the case against Klein was closed because it could not be proven that the act "was capable of causing serious fear or that [he] had any such intention".

[30] In June 2024, Klein released the singles "Luchtballon",[31] "The Bird Song",[32] and "Fußball (World Cup 1998)",[33] followed by a collaboration with Käärijä titled "Trafik!"