Marie released a successful debut single "Se nu herhen" ("Look over here") taken from her debut album I byen igen ("In the town again"). With her second solo album De her dage ("These days"), Marie became an even bigger commercial success, reaching Number. 1 on the Danish Album Charts.
Since 2002, Marie has worked with a number of musicians, firstly with her band called the Marie Key Band.
Based in Copenhagen, the band included Marie Key (lead vocals, guitar and songwriter), Jakob Thorkild (guitar), Marie Louise von Bülow (double bass and backing vocals) and Mads Andersen (drummer and backing vocals). Their genre was considered "urban popular" and their biggest hit was "KarriereKanonen 2005".