Shirley Clamp's career began as a backing singer for various singers and groups, including Antique during their Eurovision Song Contest 2001 performance to name one.

She started her solo career in 2003, when she took part in Melodifestivalen 2003 with the song "Mr. Memory". Finishing in 6th place in her semifinal, she lost the chance to qualify for the final. Her big breakthrough came in Melodifestivalen 2004 with the song "Min kärlek" (My love) composed by Ingela "Pling" Forsman. She came fourth in the last semifinal and went on to take second place at Andra Chansen, the "second chance" semifinal, thus qualifying for the final. There she was the first artist on stage, and ended 2nd, behind Lena Philipsson's immensely popular winner, "Det gör ont". "Min kärlek" won the National Finals Song Contest. A little later, in May 2004, Shirley released her first studio album, Den långsamma blomman (The Slow Flower).

In 2005 she tried once again to win Melodifestivalen, with the song "Att älska dig" ("To love you"). Shirley won the first semifinal, but in the final in Stockholm, she ended 4th. Her second studio album, Lever mina drömmar (Living my dreams) was released in April 2005. 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").

Clamp appeared at Melodifestivalen again in 2009 with the song "Med hjärtat fyllt av ljus". She placed last in the first semi-final, but eventually received a Swedish #1 single with the song. She was also a commentator for SVT during the Eurovision Song Contest 2009. Shirley returned to Melodifestivalen in 2011 with "Shirley's Angels", alongside Vera Prada and Jessica Marberger, with the song "I Thought It Was Forever." The trio competed in the third heat and advanced to Andra Chansen, where they were knocked out in the fourth duel against Pernilla Andersson.

3 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.Shirley competed in the third Semi-final and came 6th for a second time, failing to qualify for the next round.This was the 4th time she didn't make it to the final, the first being on the 2003 contest.