Mumba was born in Drumcondra, Dublin, Ireland to Peter Mumba, a Zambian aircraft engineer and Barbara, an airhostess with Aer Lingus, who is Irish; she has a brother, Omero Mumba, who is an actor. Between the ages of 3 and 15, she was a student at Dublin's renowned Billie Barry Stage School.
In 1998, she was cast as the lead in The Hot Mikado, a jazzy production based on Gilbert and Sullivan's opera. She also appeared in several Irish television shows, using the opportunity to be recognised as a singer.
At the age of 15, Mumba was discovered in a night club by Irish svengali Louis Walsh (manager of Boyzone and Westlife). Walsh was impressed by her talent and she was signed to Polydor Records, subsequently spending several months moving between Denmark, Sweden, England and Ireland, where she co-wrote and recorded her debut album, Gotta Tell You. She eventually dropped out of school to focus on her music career, citing that it was becoming a difficult task for her to stay in school and work on her music.
Mumba's first hit, Gotta Tell You, was released in 2000 and shot to the #1 spot on three Irish charts, later reaching #2 on the United Kingdom charts. She also scored American success with her debut single, peaking at #4 on the Billboard Hot 100. The album stayed on the charts for a staggering 6 months and eventually certified Platinum for shipments of 1 million copies. Five more Top 10 hits followed in the UK and another top 50 hit in the US, leading some to call her the "black Britney Spears" of pop music, although she has rejected this title. To date, her album has sold over 4 million copies world-wide. Mumba was nominated for a 2002 Grammy award for her song Baby, Come Over (This is our night) in the 'best remixed recording, non-classical' category, but did not win.
In 2002, Mumba prepared to release her follow-up album, entitled Woman, but with the poor sales of the lead single, "I'm Right Here," in both the US and UK, she was dropped from her label and the album was cancelled.
In 2012, she married Charles Porter.
In 2006, she collaborated with Filipino artist Jay-R on a new song, "Just The Way You Are", which will be featured on his upcoming album, scheduled to be released later in the year. It was stated in an article in PC World magazine that Samantha is working on her follow up album with a new label. In October 2008, three new songs "Candyland", "Turn The Beat Up" and "Bad Boy" were posted on her MySpace and YouTube profiles. In a January 2009, Mumba suggested a new would be released in 2010. She also resumed her career as an actress. She will star in the Irish Horror film "Loftus Hall" due for release in October 2010.