Anastacia was born in Chicago, Illinois into a showbiz family: her late father Robert Newkirk was a club-singer and her mother Diane Hurley an actress in Broadway musical theatre. She also has Russian origins. After her father (a manic depressive) left the Newkirk family, they moved to New York City when she was a teenager. Then she enrolled at the Professional Children's School in Manhattan.

Anastacia soon became interested in dance despite being diagnosed with Crohn's disease when she was 13-years-old. She first gained prominence stealing the show from D. L. Hughley while he was hosting BET's Comic View, singing Oleta Adams' "Get Here" in 1992. During the early 1990s, she appeared regularly on Club MTV and in a couple of videos for rappers Salt-N-Pepa. In 1999, she attracted the interest of record labels after making the finals of MTV talent show The Cut. Anastacia signed a contract with Daylight Records, a custom label of Sony BMG's Epic Records in March 1999. The Cut was hosted by Lisa "Left Eye" Lopes of R&B and hip-hop group TLC. A then-unknown Anastacia finished in second place, but impressed Lopes and the show's three judges so much that she scored herself a record deal anyway.

Her debut album Not That Kind was released in 2000. The album was a huge success, reaching the top ten in eight countries in Europe, Asia, and Oceania. It went quadruple platinum in Australia spurred by the success of her debut smash "I'm Outta Love" which was the most popular single of the year in that country for 2000. "I'm Outta Love" topped the charts in Australia and New Zealand, peaked at #2 in France and also reached number 6 in both the UK and Germany. In The US, it was only a minor radio hit. The second single "Not That Kind" reached number 11 in the UK and was a big hit all over Europe and the rest of the world. "Cowboys & Kisses" was released as the third single off the album, charting in the top 40 in some European countries. As the last single, "Made for Lovin' You" charted in the UK (27) and France (72).

While "I'm Outta Love" was a Top 10 song on the Hot Dance Club Play, "Not That Kind" did not chart high on the Billboard Hot 100.

Her second album, Freak of Nature achieved respectable sales although it did not match the level of international success of Not That Kind. The album title derives from a nickname her mother called her. The first single released was "Paid My Dues". The second single, "One Day in Your Life", reached number 11 in the UK and the top 10 in many European countries. The next single "Why'd You Lie to Me" reached the top 30 in the UK. "You'll Never Be Alone", the 4th single, reached #28 on the Adult Contemporary chart in the U.S. When the album was finally released in the United States in May 2002, she dedicated the album to Lisa "Left Eye" Lopes, who had died in a car wreck the month before. Lisa "Left Eye" Lopes was partly responsible for Anastacia's success, since Lisa hosted MTV's The Cut where Anastacia got her first break. Soon after she released a double disc edition featuring two bonus hits, remixes for three of the tracks on the album and two live tracks taken from a Japan gig that was performed on the September 13, 2002.

Anastacia joined Celine Dion, Mary J. Blige, Cyndi Lauper, Shakira, Cher, Dixie Chicks and Stevie Nicks for VH1's Divas Live in 2002 and she also contributed the song "Love Is a Crime" to the Chicago soundtrack. The song peaked at #1 on the Hot Dance Music/Club Play chart and enjoyed moderate airplay on Rhythmic/Dance format. Anastacia was selected to sing the theme from 2002 FIFA World Cup: "Boom".

In January 2003, Anastacia decided to have her breasts reduced because of back strain. From a routine mammogram for the surgery she discovered she had breast cancer. She immediately started and successfully completed surgery and radiotherapy. Anastacia subsequently established the "Anastacia Fund" to promote awareness of breast cancer among younger women.

She has attributed her health scare to being an inspiration for the sound and content of her third album. According to an interview she made in 2005 on a British music station The Box, her voice lost its power and she became unable to record and thus she spent a long time writing and trying to create a sound she would be finally happy with.

As she said on Rove (Australia) in 2004, she wanted to have more edge to her vocals as she felt there was something missing from her previous works. She brought in many rock instruments which brought a new atmosphere to her music. She also felt that she still needed the funkiness and the pop as the singer felt that too much edge would sound wrong with her voice. Out of this a new sound was formed. She describes her sound as "sprock" - a combination of soul, pop and rock. She named the album after herself.

Anastacia entered record studios in September 2003 to begin recording her next album, working with Glen Ballard, Dallas Austin, and Dave Stewart for release in 2004. On the album, Anastacia also collaborated with P.O.D. lead singer Sonny Sandoval on the socially-conscious track "I Do".

The first single, released in March, was "Left Outside Alone", which saw a change in direction for Anastacia. Anastacia proved to be a smash hit reaching the top of the album charts in the United Kingdom, Ireland, the Netherlands, Australia, Greece, Germany, and Italy and number 2 in Portugal and Spain. "Left Outside Alone" proved to be equally successful reaching number 1 in Australia, Spain, Italy, Austria and Switzerland; number 2 in the Netherlands + Germany, number 3 in the UK and reaching the top 5 on the composite European chart. Unlike her first two albums, which were released in her homeland of America, Anastacia was not, despite being scheduled for release on three occasions. "Left Outside Alone" was released twice, but failed to pick up heavy airplay. It only gained sporadic Adult Contemporary and Hot AC format airplay. Again, it sparked Rhythmic/Dance format airplay and the dance mix of "Left Outside Alone" peaked at #1 on the Hot Dance Music/Club Play. After the original version of "Left Outside Alone" failed to catch on because of lukewarm promotional pushes, especially on radio, the album was postponed and eventually cancelled after the release date of August 30, 2004 passed.
Anastacia released three further internationally successful singles; "Sick and Tired" (which gave her another #1 in Spain and another UK Top 5 single), "Welcome to My Truth" (her best-selling hit in Spain), and the ballad "Heavy on My Heart" proceeds from the sale of which went towards her 'Anastacia Fund' (a charitable organization providing research funding for breast cancer).

A small batch of Anastacia the album was released with a bonus DVD, Anastacia poster and slip case. The DVD includes "Making Of Anastacia", "2002 Europe Promo Tour" and a photo gallery.

From September 2004 to August 2005, Anastacia went on a "Live at Last Tour". By 2005 the tour was renamed the "Encore tour".

In late 2005, she released her first greatest hits collection, called Pieces of a Dream, named after a track of the same name. The album spawned the hit singles "Pieces of a Dream" and the duet with Eros Ramazzotti "I Belong to You", which was a huge hit in Europe, charting and peaking in the top ten in almost all the European countries. Even though Sony BMG did force her to release this collection, Anastacia says she is happy now that it was created as it was like a "story book", or summary of the first five years of her career.

Not long after the release of "I Belong to You", Anastacia released her first live DVD Live at Last on March 27, 2006 in Europe. The DVD contains footage from concerts in Berlin and Munich. It includes music videos to her four singles ("Left Outside Alone" , "Everything Burns" , "Pieces Of A Dream" and "I Belong to You", with Eros Ramazzotti), five alternative videos (I Do, Rearview, Seasons Change, Underground Army and Time) to songs from her self named album, and a documentary about the tour.

Anastacia attended the memorial Concert For Diana on July 1, 2007, which would have been on Diana's 46th birthday. This was one of the first major events to take place in the new Wembley Stadium, and one of her first major appearances since she took a break from the industry. She opened the medley section of the show and she sang a rendition of "Superstar", from Andrew Lloyd Webber's Jesus Christ Superstar, with a gospel chorus behind her.

In August 2007, a video was put on the "Anastacia by S. Oliver" web site. During the video, when Anastacia was asked about her future plans, she confirmed that she was working on a new album as well as the clothing line. A specific month of release or title was not mentioned. In November 2007, her biography on the official Anastacia website was updated to say there will be a new album in 2008, with a tour to follow.

On July 24, Anastacia announced that her long awaited fourth studio album Heavy Rotation will be released October 27, 2008 in Europe and Asia (and elsewhere in 2009). The new album will feature collaborations with producers Ne-Yo, The Heavyweights, Lester Mendez, JR Rotem and Rodney Jerkins. The album's first single, called "I Can Feel You", began playing in some radio markets on August 25, 2008. The second single from Heavy Rotation is "Absolutely Positively".