2002–2003: Deutschland sucht den Superstar

In 2002, Klaws was encouraged by his family and friends to audition for the debut season of the reality television series Deutschland sucht den Superstar. Although he was considered as one of the more inconspicuous top ten finalists at the very beginning of the show, he was able to boost his popularity constantly with standout performances of Robbie Williams' "Angels" or Michael Sembello's "Maniac". Klaws went on to win the competition on 8 March 2003, earning 70.1% of the votes against runner-up Juliette Schoppmann and without being sent into the bottom three throughout the season.

Immediately after winning DSDS, Klaws was signed to a record deal with Sony BMG, while jury member Dieter Bohlen was consulted to produce his debut album on the company. On 17 March 2003 his debut single, "Take Me Tonight" was released. The song was performed by Klaws during the season finale of DSDS. The song subsequently debuted at number 1 in Germany and Switzerland. It eventually went on to become the second best-selling single of 2002 behind "We Have a Dream" and was certified quintuple gold by the Bundesverband Musikindustrie (BVMI). In May he followed up with his debut album Take Your Chance, which saw similar success and spawned a second single "Stay with Me". At the end of a year he entered the top of the charts again with "Free Like the Wind", the soundtrack to the German TV movie Hero of the Gladiators.

On 25 December 2003, Klaws participated in the television special competition World Idol in London along the inaugural winners of the several Idol television series around the world. He was contractually obligated to participate, and performed Michael Sembello's "Maniac". On 1 January 2004 he finished ninth in the competition.^[1]

2004–2006: Career development

Here I Am, Klaws's second album, was released in July 2004.^[2] A musical continuation of his commercially successful debut, he worked with a small number of new collaborators on the album apart from Bohlen, including Yak Bondy, Ingo Politz, and Brix.^[2] Like its predecessor, the album debuted atop the German Albums Chart and reached the top ten in Austria and Switzerland, but it ultimately failed to live up to the overwhelming success of his debut album.^[2] In spite of this, the album managed to snag Klaws another three hit singles, including the top five hits "Behind the Sun" and "Sunshine After the Rain" as well as the top 20 entry "Here I Am".^[2] Also in 2004, Klaws was cast in a supporting role in an episode of the German television series Das Traumhotel, filmed in Bali and broadcast the following year.^[2]

In March 2005, he recorded and released the duet "All (I Ever Want)", an English version of the 3 Musketiers theme song featuring vocals from German singer Sabrina Weckerlin. The original version of the duet, "Alles" was released to promote the RTL television film Hero of the Gladiators (2003). The English version of the song peaked at number 12 on the German Singles Chart was later included on his third album, Attention! (2006).^[2] Recorded after a short-living hiatus from recording in which she had studied song and acting at the Joop van den Ende Academie in Hamburg, it marked a departure from Klaws's previous work with Bohlen, who gained no credit on the record. Instead, Klaws consulted a wider range of producers to work with him on the album, including Terri Bjerre, Thorsten Brötzmann, and Ivo Moring, who took his work further into the pop rock genre. Upon its release, Attention! became a top 20 success in Austria and Germany only, prompting Sony BMG not to release another single from the album.^[2]

2007–present: Musical theatre

Klaws performing in 2008

In December 2006, Klaws made his musical theatre debut at the Theater des Westens stage in Berlin in 2006, playing the role of Alfred in the musical remake of Roman Polanski's satirical horror drama Dance of the Vampires (1967).^[2] Following the conclusion of his management and recording contract, he signed a new deal with Cruiser Entertainment which released his fourth album Was willst du noch?! through Edel Music in April 2008. His first album to be primarily recorded in German, it peaked at number 28 on the German Albums Chart and produced two singles.^[2] In 2010, Klaws took over the role of Tarzan in the Neue Flora Hamburg production of the same-titled musical based on the Walt Disney Animation Studios 1999 film of the same name. Running for five years, it closed in 2013.^[3]

Klaws collaborated with frequent collaborators Thorsten Brötzmann and Ivo Moringa on his fifth album Für alle Zeiten. Released in September 2011, it reached the top fifty of the German Albums Chart and produced several singles, including "Himmel und Hölle".^[2] In April 2013, he served as a supporting act throughout the German leg of British singer Leona Lewis's Glassheart Tour.^[2] The same year, Klaws played the role of Ranger in the musical version of the German comedy film Der Schuh des Manitu at the Freilichtbühne Tecklenburg.^[2] He returned to Tecklenburg the following year, portraying Joseph in a local production of Andrew Lloyd Webber's Joseph and the Amazing Technicolor Dreamcoat.^[2] He followed it with a role at the Theater Dortmund, starring as Jesus in an adaptation of Lloyd Webber's rock opera Jesus Christ Superstar.^[2]

Klaws fifth studio album Auf die Bühne, fertig, los! was released in October 2015 and reached the top forty of the German Albums Chart.^[4] In 2016, he reprised both of his roles as Jesus and Tarzan at the Theater Basel and at the Metronom Theater in Oberhausen, respectively.^[2] Also that year, he starred as Tony Manero in a local production of Saturday Night Fever at the Freilichtbühne Tecklenburg.^[2] In summer 2017, he played Old Surehand at the Karl May Festival in Bad Segeberg.^[2] In December 2017, he originated the role of Sam in the German version of Ghost the Musical, based on the hit 1990 romantic fantasy thriller film of the same name, for which he returned to the Theater des Westens stage in Berlin.^[2]

In 2021, Klaws won the fifth season of The Masked Singer.^[5]