Her big breakthrough came in Melodifestivalen 2004 with the song "Min kärlek" (My love) composed by Ingela "Pling" Forsman.

There she was the first artist on stage, and ended 2nd, behind Lena Philipsson's immensely popular winner, "Det gör ont".

A little later, in May 2004, Shirley released her first studio album, Den långsamma blomman (The Slow Flower).

A year later, she released Favoriter på svenska, a special covers album, containing songs with lyrics in Swedish, such as Roxette's "It Must Have Been Love" ("När kärleken föds").

The trio competed in the third heat and advanced to Andra Chansen, where they were knocked out in the fourth duel against Pernilla Andersson.

Three years laters she tried her luck participating at Melodifestivalen 2014 with the song "Burning Alive" which was composed by Bobby Ljunggren, Marcos Ubeda, Sharon Vaughn and Henrik Wikstrom.