Knowles reportedly started working on her third studio album in December of 2007. The album is titled I Am… Sasha Fierce Knowles says that the name Sasha Fierce is the name of the persona she adopts when she performs onstage. "That is my alter ego and now she has a last name," says Knowles. "I have someone else that takes over when it's time for me to work and when I'm on stage, this alter ego that I've created that kind of protects me and who I really am." In an interview with producer Rodney Jerkins, he said that the style of the album kept switching and was inspired by Knowles' upcoming film, Cadillac Records, in which Knowles had been cast to play famed blues singer Etta James, he also mentioned that the release date she was working at for the album was November 2008.

Knowles recorded a cover of Billy Joel's "Honesty" which was included on a Matthew Knowles/Music World CD released only in Japan towards the end of June 2008 to celebrate the tenth-year anniversary of Destiny's Child. Knowles also recorded with various artist for "Just Stand Up!", a charity single for the "Stand Up To Cancer" charity. This charity aims to raise funds for cancer research through the acts and offerings of the celebrity world. Joining Knowles on this charity single was Mariah Carey, Natasha Bedingfield, Leona Lewis, Rihanna, Leann Rimes and Mary J. Blige. The song was brought to public attention recently when it was performed live by most of the stars at Fashion Rocks 2008 in New York City—this show was broadcast simultaneously on all major American networks on September 5, 2008.

"If I Were a Boy" and "Single Ladies (Put a Ring on It)", the first singles from I Am… Sasha Fierce, were released to radio on October 14, 2008, preceding the album's release on November 18, 2008. While the single "If I Were a Boy" became Knowles' fourth UK number-one single, "Single Ladies (Put a Ring on It)" went on to top the December 13, 2008 issue of the Hot 100 chart, giving Knowles her fifth number one single in the U.S. In addition to releasing a new album and continuing her growing film career with the upcoming release of Cadillac Records, Knowles will also star opposite Ali Larter and Idris Elba in a thriller film called Obsessed, which has been in production since May 2008. This film is due in the United States in January 2009, with an international release slated in March 2009.

Knowles will tour the world for most of 2009, starting in the Spring and visiting venues all over the world from the America's, Europe, Asia, Africa and Oceania. Knowles will also include a week long stint of shows in Las Vegas. The tour will be named "Beyoncé's I Am... Tour" will visit cities such as Zagreb, Budapest, Paris, London and Manchester.

• Obsessed (2009) (completed) .... Beth Charles
• Cadillac Records (2008) .... Etta James
• Dreamgirls (2006) .... Deena Jones
• The Pink Panther (2006) .... Xania
• The Fighting Temptations (2003) .... Lilly
• Austin Powers in Goldmember (2002) .... Foxxy Cleopatra
  ... aka Austin Powers: Goldmember (USA)
• Carmen: A Hip Hopera (2001) (TV) .... Carmen
• Beverly Hood (1999) (uncredited) (unconfirmed) .... Girl #1
• "Dancing with the Stars" (1 episode, 2008)
       - Round 6 (2008) TV episode (performer: "Irreplaceable")
• Karaoke Revolution Presents: American Idol Encore (2008) (VG) ("Irreplaceable")
• Bling: A Planet Rock (2007) ("Grillz")
• Good Luck Chuck (2007) (writer: "Crazy in Love")
• "The Pussycat Dolls Present: The Search for the Next Doll" (1 episode, 2007)
       - Welcome to the Dollhouse (2007) TV episode (writer: "Crazy In Love")