She is a professional classical lied singer with a three-octave vocal range,[1] and founded symphonic metal band Nightwish with Tuomas Holopainen and Emppu Vuorinen in 1996.

Their combination of hard and fast guitar riffs with Turunen's dramatic, "operatic" lead vocals quickly achieved critical and commercial popularity.

On 17 November 2017, she released her second Christmas album, From Spirits and Ghosts, putting a dark orchestral twist on various classic holiday songs.

Her talent for music was first noted when she sang the song "Enkeli taivaan" (the Finnish version of "From Heaven Above to Earth I Come") in the Kitee church hall at age three.

At the recording session for the first demo Holopainen discovered that due to her classical singing lessons, Turunen's voice had become much more powerful than he recalled from their school days.

Holopainen used this material to convince the Finnish label Spinefarm Records to publish the band's debut album, Angels Fall First.

This album lacked the earlier elements of folk and ambient music, and instead focused on fast, melodic keyboard and guitar lines and Turunen's dramatic voice.

[20] In addition to the Nightwish tour in 1999, Turunen sang solo in Waltari's rock-themed ballet Evankeliumi (also known as Evangelicum) in several sold-out performances at the Finnish National Opera.

Turunen enrolled in 2000 at the German music university Hochschule für Musik Karlsruhe to gain a professional qualification as a soloist with further specialization in art song.

[25] In 2002, Turunen toured South America, performing in the classical Lied concert Noche Escandinava (Scandinavian Night) to sold-out houses.

Following this and an exhausting world tour in support of Century Child, Nightwish took a hiatus and Turunen returned to Karlsruhe to finish her studies.

For Christmas 2004, Turunen released her first solo single, titled "Yhden enkelin unelma" (One Angel's Dream), which sold gold in her native country of Finland.

He answered questions related to the greed accusation by explaining that the band had agreed on the distribution of earnings in a contract at the formation of Nightwish.

[41] Turunen again played at the Savonlinna Opera Festival in July 2006, this time as the main act; she sang alongside Finnish tenor Raimo Sirkiä, supported by the Kuopio Symphonic Orchestra.

On 6 December 2006, Turunen performed a big concert at the Sibelius Hall in Lahti, Finland; it was broadcast live by the Finnish channel YLE TV2 for 450,000 viewers.

[45] Turunen released My Winter Storm, an album featuring various styles, including symphonic metal with classical "operatic" lead vocals, in November 2007.

In December 2009 she recorded her vocal part for the song "The Good Die Young", a duet with Klaus Meine which is included on the final Scorpions album Sting in the Tail.

[54] On 17 July 2011, she sang again at the Savonlinna Opera Festival along with acclaimed tenor José Cura and accompanied by the Kuopio Symphony Orchestra.

[57] In January 2014, Turunen revealed through her blog that she would soon return to the studio and record vocals for a couple of songs for her Outlanders project together with Torsten Stenzel & Walter Giardino.

[68][69] On July 27, 2018, Tarja released Act II, a live album and DVD recorded during the concert on November 29, 2016, at the Teatro della Luna in Milan, during the world tour The Shadow Shows.

On 23 June 2023, Tarja and EDM producer Torsten Stenzel released their self-titled debut studio album under the moniker of Outlanders.

She explained that in the early days of Nightwish, it was difficult to combine classical technique with the metal sound in a way that gave her liberty of action without damaging her vocal cords.

[86] Towards the turn of the millennium, the combination of hard and fast guitar riffs with classical female lead vocals attracted a great deal of attention in the metal scene.

[93][94] A challenge of a different kind was the cover version of Gary Moore's "Over the Hills and Far Away" (2001), as it required a deeper voice, far below the vocal range of an average soprano.

In an interview with Breakout magazine, she reported that in the studio, the band members were shaken by a paroxysm of laughter as she tried to warm up for the vocal lines.

For the album Century Child (2002), she experimented with a more "rock" sounding voice, where she maintained the classical singing technique, but, for example, sang with less vibrato.

Like a phoenix from the ashes [...] she lifts up again and again for widely arching melodies, sometimes spurred on by multi-voiced female choirs.In an interview, she explained that My Winter Storm was the first album where she had the chance to use her full vocal range.

[108] In December 2013, Turunen was the invited soloist at the Christmas Peace event in the Turku Cathedral, Finland, with the presence of Finnish president Sauli Niinistö.

[114] Turunen married Argentine businessman Marcelo Cabuli on 31 December 2002 – their wedding was celebrated in July 2003; they lived in Buenos Aires with their daughter who was born in 2012.

In an interview, Tarja explained that in 2016 they had plans to move back to Europe due to her touring schedule and that their daughter was starting school in the coming year.