K3 is a Belgian-Dutch girl group with a Dutch-language pop repertoire, consisting of Hanne Verbruggen, Marthe De Pillecyn and Julia Boschman. The group's name is derived from first letters of the three first members from 1998: Karen Damen, Kristel Verbeke and Kathleen Aerts. Their signature style and iconocity relies in all three girls mostly wearing the same outfit, and in the fact that each girl's hair represents one color in the Belgian flag. Throughout their career, K3 has built a space within Dutch and Belgian pop culture.

The rise to fame of K3 began with their running to represent Belgium in the 1999 Eurovision Song Contest with the single "Heyah Mama", eventually losing to Vanessa Chinitor's "Like the Wind". Despite receiving mixed reviews from the judges, the song peaked at two in Belgium (Ultratop 50 Singles) and at eighteen in The Netherlands. It was included in the debut album Parels (1999), which also met great commercial success in both countries. The band's rise to fame surprisingly came without any airplay from the regular music television channels like MTV and are directed towards kids and chose to market itself directly to children via cartoon television channels. The group later signed with Bertelsmann Music Group and released the albums Alle Kleuren (2000) and Tele-Romeo (2001).

In 2002, K3 departed ways with BMG and signed family entertainment production company Studio 100, opting for a more children-orientated direction. From 2002 to 2009 K3 recorded six more albums, all of them peaking at number one both in the Netherlands and Belgium, had their own children's television series called De Wereld Van K3 (2003-13), toured the Benelux eleven times with a total attendance of 1,7 million, and had starred in three cinema movies: K3 en het Magische Medaillon (2004), K3 en het IJsprinsesje (2006) and K3 en de Kattenprins (2007) that generated a $9,1 million revenue. Despite the outstanding success of the group, Kathleen Aerts stepped out of the formation in March 2009. She was replaced by Josje Huisman later that year after winning audition reality show K2 Zoekt K3.

The first single with Huisman as part of the group, "MaMaSé!", became a smash hit, peaking at number one for six consecutive weeks in The Netherlands and for seven weeks in Belgium. It listed in the top three of both countries' year-end charts. The album of the same name entered the year-end album chart in both countries in 2009, 2010 and 2011. With Huisman, K3 recorded five more albums, produced and starred in the first 3D-musical in the world, based in Lewis Carrol's Alice in Wonderland, taped two more movies: K3 Bengeltjes (2012), which became the group's highest-grossing film with a $5,1 million revenue, and K3 Dierenhotel (2014), and had their own sitcom series Hallo K3! (2011-12), which lasted three seasons, and K3 Kan Het! (2015).

On 18 March 2015 Damen, Verbeke and Huisman announced through a press conference that they were all leaving the group stating "since we started, we knew there would be a time which we would feel that it was the accurate moment to stop; well, that moment is now present". A second audition television show, K3 Zoekt K3, premiered in autumn to find the new K3 members. Hanne Verbruggen, Klaasje Meijer and Marthe De Pillecyn won the contest. Their first release, "10.000 Luchtballonnen" topped the charts in Belgium and The Netherlands. From 2015 to 2021, the group released six albums, starred in two more films: K3 Love Cruise (2017) and K3 Dans van de Farao (2020), had their own animated series De Avonturen van K3 (2016) and became television judges on seasons four and five of the Flemish version of The Voice Kids. In 2021, Meijer left the group and was later replaced with Julia Boschman.