Born Eilleen Regina Edwards, in Windsor, Ontario, to Sharon and Clarence Edwards, her name was changed to Eilleen Twain after her parents separated when she was two, and her mother remarried to Jerry Twain, a full-blooded member of the Ojibwa First Nation. She grew up in Timmins, Ontario.

Eilleen Twain had a hard childhood; with her parents not earning much, Twain was sent out to sing in numerous clubs and bars to help bring the money in, encouraged and mentored by her mother, Sharon, who often fell into bouts of depression over the lack of food in the household.

At the age of 13, Eilleen Twain was invited to perform on CBC television's Tommy Hunter Show. During high school in Timmins, she was the vocalist for a local band "Longshot" which covered Top 40 music. When her mother and adoptive father died in a car accident on November 1, 1987, Eilleen put her musical career on hold, and was forced to take care of the family. She took her two younger brothers, Mark and Darryl, and sister Carrie-Ann to Huntsville, Ontario, where she supported the family by performing at a local resort (Deerhurst resort). In 1991, after an entertainment lawyer (Dick Frank) from Nashville, Tennessee heard her act, she was invited to record a demo tape.

In 1991, when she signed her first recording contract with Richard Frank of Mercury Nashville Records, she changed her name to Shania (pronounced shu-NYE-uh) which is an Ojibwa word meaning "I'm on my way". Twain's embrace of her adoptive Ojibwa heritage has at times been reported to be controversial among Canadian First Nations, with some disagreement about whether a non-Ojibwa adopted by an Ojibwa parent can be considered a true Ojibwa. Shania Twain responded to such criticism by saying, "I don't know how much Indian blood I actually have in me, but as the adopted daughter of my father Jerry, I became registered as a 50% North American Indian ... That is my heart and my soul, and I'm very proud of it."

The city of Timmins later renamed a street for her, gave her the key to the city and built the Shania Twain Museum (Shania Twain Centre), which Twain visited in 2004, as shown on a CTV special.

Twain felt her 1993 self-titled debut album was unsatisfactory as she was forced by her record company to work with Nashville songwriters, and she only got to co-write one of the songs, and felt that the album was not really her own.

The album didn't please the public, gaining little sales and no real chart action for its singles. The albums first two singles, "What Made You Say That" and "Dance with the One That Brought You", as well as the album all peaked at #55 on Billboards Country Charts. By the end of 1993 the album sold less then 250,000 copies.

Twain immediately felt alienated from the Nashville music scene, as she felt the album lacked her passion and drive for country music. Thankfully for her, things changed when she met Mutt Lange at Nashville Fan Fair.

Everything changed when rock producer Robert "Mutt" Lange heard Shania's original songs and singing and thought she held promise. He offered to produce her and to write songs with her. After many telephone conversations, they met in person at Nashville's Fan Fair in June 1993. Soon their professional relationship took a romantic turn, and they were married on December 28, 1993.

Lange and Twain instantly formed a successful partnership, and Twain has often commented that a reason they work so well is because they are so different; after all, Lange is 17 years older than she is. They started working on a second album, and in 1995 The Woman in Me caught fire due to singles like "Any Man of Mine" and "Whose Bed Have Your Boots Been Under?", because the videos were saucier than anything that Nashville had ever seen before; it was clear that Twain wanted to make her mark. The album eventually topped the country charts for months and became a massive crossover to mainstream charts, peaking at No. 5 and to date has sold over 12 million copies. The Woman in Me went on to win the Grammy Award for Best Country Album as well as the Academy of Country Music award for Album of the Year; the latter group also awarded Twain as Best New Female Vocalist.

In 1997, Twain released her follow-up album, Come on Over. This was the album that established Twain as a successful crossover artist. Selling 172,000 copies out of the gate, the album was seen by many at first as a disappointment, given the massive success of her last effort. But slowly, the album started racking up sales. It never hit the top spot, but with the multi-chart hit single "You're Still the One", sales skyrocketed. Songs like "Don't Be Stupid", "Honey, I'm Home", "Man! I Feel Like a Woman!", "That Don't Impress Me Much", and "From This Moment On" joined the 12 songs that eventually saw release as singles. Over the next two years, the album stayed on the charts, spinning off hit after hit. When the dust finally settled, Come on Over had sold 20 million copies in the United States and 39 million worldwide, making it the biggest-selling album of all time by a female artist, the biggest-selling country album of all time, and the No. 6 selling album of all time.

Songs from the album won four Grammy Awards over the next two years, including Best Country Song for Twain and Lange for "You're Still the One" and "Come on Over" and Best Female Country Performance for "You're Still the One" and "Man! I Feel Like a Woman!". The album has sold 39 million copies worldwide, the largest ever by a female solo artist, but despite this it wasn't able to top the Billboard 200, reaching a peak of #2. It did however top the charts for 11 weeks in the UK. Additionally, the album set the record for the longest ever stay in the Top 20 of The Billboard 200, remaining in the Top 20 for 99 weeks (about 1 year and 10 months).

There were several keys to this success. The songs on Come on Over were full of catchy hooks and phrases that proved memorable. Lange's hard rock production techniques from his work with Def Leppard, AC/DC and others proved effective in the country/pop context. Many newer fans were unaware of her country music roots, particularly as versions of singles released to non-country radio in North America and around the world featured remixed versions de-emphasizing country-style instrumentation.

Twain's mainstream pop acceptance was further helped by her appearance in the 1998 first edition of the VH1 Divas concert, where she sang alongside Mariah Carey, Céline Dion, Gloria Estefan, and Aretha Franklin, and by VH1's 1999 heavily-aired Behind the Music treatment of her, which concentrated on the tragic aspects of her early life as well as her physical attractiveness and Nashville's early resistance to her bared-midriff music videos. In 1999 Twain also established a visible commercial relationship with Revlon cosmetics, based around "Man! I Feel Like a Woman!".

In 1998 Shania Twain launched her first major concert tour, aided by her manager Jon Landau, a veteran of many large-scale tours with Bruce Springsteen. The shows were enthusiastically received by audiences around the globe and answered critics who speculated that she could not perform live. As part of this tour, she held a contest in each city that she visited to allow one young singer to join her on stage for one of her songs. One of these lucky winners was Avril Lavigne who sang with Twain at her concert in Ottawa. Twain's peak of success was further emphasized when she was named the 1999 Entertainer of the Year by both the Academy of Country Music and the Country Music Association. She is the first of only two non-Americans and one of only five solo women to win the CMA version of the award. The other non-American is Keith Urban, and the other solo women are Reba McEntire, Barbara Mandrell, Dolly Parton, and Loretta Lynn.

After taking time off and having a child, Eja [pronounced Asia] in 2001, Shania Twain went back into the studio. Up! was released in November 2002, making it five years since the world had new material from her, and she toured again to promote it. Twain and Lange were reported to have taken it easy during this break, as Twain wanted a two year break due to exhaustion. They drank lots of hot chocolate, rode horses and relaxed in their Switzerland mansion, according to the singer. They toured over the world greatly, and recorded and wrote the material for the new album in many different countries, from Berlin to Mumbai. A double album, it featured 19 songs in pop mixes and the same 19 songs in country mixes. Internationally the country mixes were replaced by world music mixes, the instrumentation of which featured non-classical Indian music styles. The International remixes were recorded in Mumbai, India. Up! was given 4 out of 5 stars by Rolling Stones magazine, and debuted at No. 1 on the Billboard albums chart, selling 874,000 in the first week alone. It charted at the top for five weeks.

The first single from the album "I'm Gonna Getcha Good!", became a modest country hit that didn't do much on the pop charts, while the follow-up single "Up!" failed to hit the top ten country or the top 40 pop. However, the third single from the album would be the most successful. The romantic ballad "Forever and for Always" was released as a single in April 2003 and peaked at number four on the country chart and number one on the AC chart, spending 6 weeks there. "She's Not Just a Pretty Face" was a country top-ten hit, while the last single, "It Only Hurts When I'm Breathing", debuted on her fifth TV special Up! Close and Personal, made the top 20 on both Country and AC. Internationally, Twain had great success with exclusive releases of "Ka-Ching!", "Thank You Baby! (for Makin' Someday Come So Soon)", and "When You Kiss Me", particularly in countries such as Germany and the UK. To date, Up! has gone 11 times platinum in the U.S., and has sold over 17 million copies worldwide. These are very impressive marks by normal standards, despite not being as high as the records set by "Come on Over".

Also in 2003, Twain participated in the Dolly Parton tribute album, Just Because I'm a Woman, covering Parton's classic "Coat of Many Colors". (On a number of occasions, Twain has cited Parton as one of her greatest musical influences.)

In 2004, she released the Greatest Hits album, with three new tracks. To date, it has sold over three million copies in the U.S, and over 7 Million worldwide. The first single, the multi-format duet "Party For Two", made the country top ten with Billy Currington but the pop version with Sugar Ray lead singer Mark McGrath made the top 10 on the UK singles chart. Two further singles did not do much on any chart, although "Don't!" was featured in the film An Unfinished Life and "I Ain't No Quitter" showed Twain's fans, that despite the fact that she had mastered a successful change into the world of pop, her country roots were still very dear to her. Twain received a lot of criticism from CMT for the gestures made in the video to "I Ain't No Quitter", but Twain simply ignored them; as she once said "I find that the very things that I get criticized for, which is usually being different and just doing my own thing and just being original, is the very thing that's making me successful."

After the singles were released from Twain's Greatest Hits, Twain announced she would be going back into the studio to work on a new album, however she was unsure of what she wanted to do, musically. Mercury Records, Twain's recording label, have denied that a new single and album will be out by the end of the year, but other unofficial sources have claimed that there will be - the matter is still undecided.

However, Twain was recently seen at a Toronto airport which may tie along into the Czech news story back in the spring that Twain would be filming a new music video in Canada this summer.

Although there are now rumours circulating the internet of a possible release of an album in November called So Happy, with a lead single called "Don't Shoot The Messenger".

Twain recently bought some land near Wanaka in New Zealand, at a 170 km² sheep station where she hopes to build a house, despite much criticism in its purchase from neighbours. Her Swiss Chateau, is currently on the market for $25m US.

Twain celebrated her 40th birthday in August 2005, and in the same month she released the single "Shoes" from the Desperate Housewives soundtrack; it failed to make much of an impact, barely getting into the top 30 on the country charts and not charting elsewhere. Shoes was also the first single release in which she and her husband were not the entire writing credits since her first album (besides the promotional release of Coat of Many Colors from the album Just Because I'm A Woman: Songs of Dolly Parton.

A television biopic of Twain, Shania: A Life in Eight Albums, aired on CBC Television on November 7, 2005, with Meredith Henderson starring as Twain.

In 2005 Twain would add a commercial relationship with COTY, for the creation of her fragrance Shania by Stetson. Around the same time, Twain appeared on an episode of the reality show The Apprentice, riding horses around Central Park and having dinner with two contestants who had successfully marketed her fragrance on the show.

On November 18, 2005, Twain was invested as an Officer in the Order of Canada.

Shania has also been confirmed as one of the recipients of a star on the Hollywood Walk of Fame, to be awarded in 2007.

Twain has always been known for her beliefs, and always stands up for them. She and her husband are strict vegetarians, and she once said 'Nothing that has to die' in regards to her vegetarianism; and it is believed that she has raised her son, Eja, vegetarian until he is old enough to decide for himself.

After The Woman in Me was released, everyone expected her to tour, but Twain declined. Her reasons for this were that she didn't want to tour with songs that weren't her own, as to stage a good tour, she would need to use material from her first self-titled album, which she didn't want to do as she only co-wrote one of the ten songs on it. Critics immediately declared that she couldn't sing, and was just a Mutt Lange studio product; but Twain proved everyone wrong when she toured after Come on Over, and she broke records for the number of tickets sold on this tour. On her most recent tour, Up!, she designed the stage so that it was a round one, and happily signed autographs for fans whilst singing.

She is also a great supporter of charities which help feed 'hungry kids across North America'. These include the Second Harvest Kids Bag and Kids Cafe, and to show her support, she released the song "God Bless the Child" in 1996, with all proceeds from it going to her favourite charities.

"Black Eyes, Blue Tears" was a song that Twain specifically wrote to encourage and inspire 'bruised and battered women', suffering domestic violence; Twain believes in the power of music, that it can change a person and send a very powerful message.