Ketevan Melua, known as Ketino to her family, was born in 1984 in Georgia, then part of the Soviet Union, in Kutaisi and spent her first years with her grandparents in Tbilisi. Later she moved with her parents and brother to the town of Batumi, Ajaria where her father worked as a heart specialist. During this time Melua sometimes had to carry buckets of water up five flights of stairs to her family's flat and according to her, "Now, when I'm staying in luxurious hotels, I think back to those days..." In 1993, in the aftermath of the Georgian Civil War, the family moved to Belfast, Northern Ireland, where her father took up a position at the prestigious Royal Victoria Hospital. The family remained in Belfast, living close to Falls Road, until Melua was thirteen. During her time in Northern Ireland, Melua attended St. Catherine's Primary School on the Falls Road and later moved to Dominican College, Fortwilliam. This is where Melua learned most of her English. Then the Melua family moved to Sutton, London, and some time later moved again to Redhill, Surrey. Melua recently moved just a few kilometers away from her parents' home in Maida Vale to an apartment in Notting Hill where she transformed the spare bedroom into a recording studio. Melua speaks Georgian, Russian and English and is partly of Canadian and Russian ancestry.

During the South Ossetia War in 2008, Melua's brother and mother were staying with relatives in the Georgian capital, Tbilisi. Melua was due to travel to Georgia herself just two weeks later.

Because of her upbringing in politically unstable Georgia and troubled Belfast, Melua initially planned to become either a historian or a politician. This changed in 2000, at the age of 15, when Melua took part in a talent competition on British television channel ITV called "Stars Up Their Noses" (a spoof of Stars in Their Eyes) as part of the children's programme Mad for It!. Melua won the contest by singing Badfinger's "Without You". The prize was £350 worth of MFI vouchers, with which she bought a chair for her father. Had she lost the contest, she would have been gunged.

Although she is a baptised Orthodox Christian, whilst living in Belfast, Melua attended the Roman Catholic schools St Catherine's Primary School and Dominican College, Fortwilliam, while her younger brother attended Protestant schools. After completing her GCSEs at the all-girls' grammar school Nonsuch High School in Cheam, Sutton, Melua attended the BRIT School for the Performing Arts in the London Borough of Croydon, undertaking a BTEC with an A-level in music. She began to write songs when at the school. Melua first met her future manager, producer Mike Batt, when studying at the school.

Melua didn't attend University, though she has often stated her desire to do so, saying that English literature, history and physics would be her courses of choice should she get the chance to go to University.

On 10 August 2005, Melua became a British citizen with her parents and brother. The citizenship ceremony took place in Weybridge, Surrey. On gaining British nationality, Melua was eligible for a British passport, which makes it easier for her to travel around the world. Becoming a British citizen meant that Melua had held three citizenships before she was 21; first Soviet, then Georgian and finally British. After the ceremony, Melua stated her pride at her newest nationality. "As a family, we have been very fortunate to find a happy lifestyle in this country and we feel we belong. We still consider ourselves to be Georgian, because that is where our roots are, and I return to Georgia every year to see my uncles and grandparents, but I am proud to now be a British citizen.

It was when performing at a Brit School showcase that Melua caught the eye of Mike Batt, an English songwriter and producer who was originally looking for an acid-rock band, bass player and a singer capable of singing "jazz and blues in an interesting way". After hearing Melua sing "Faraway Voice" (a song she wrote about the death of her idol Eva Cassidy) Batt signed the 18 year-old Melua to his small Dramatico recording and management company and sent her into the studio.

Call off the Search featured two songs written by Melua: "Belfast (Penguins and Cats)", a song about Melua's experience of her time in the troubled capital of Northern Ireland, and "Faraway Voice", a song about the death of Eva Cassidy. Melua also covered songs by Delores J. Silver ("Learnin' the Blues"), John Mayall ("Crawling up a Hill"), Randy Newman ("I Think it's Going to Rain Today") and James Shelton ("Lilac Wine").Originally a major U.K. hit for singer Elkie Brooks. A final six songs on the album were by Mike Batt.

It was initially difficult for Melua and Batt to get airplay for the album's lead single, "The Closest Thing to Crazy". This changed when BBC Radio 2 producer Paul Walters heard the single and played it on the popular Terry Wogan breakfast show. Wogan played "The Closest Thing to Crazy" frequently in November and December 2003 in an attempt to make it that year's Christmas number-one. The single only reached number 10, but Wogan's support raised Melua's profile and when Call off the Search was released it became an immediate hit, reaching number one on the UK albums chart in January 2004. Call off the Search reached the top five in Ireland, top twenty in Norway, top thirty in a composite European chart and top fifty in Australia. In the UK, the album sold 1.2 million copies, making it four times platinum, and spent six weeks at the top of the charts. It sold three million copies worldwide. Subsequent singles did not reach the success of the first — the second single and album title track, "Call off the Search", reached number 19, and the third single, "Crawling up a Hill", got to number 41.

Melua's second album, Piece by Piece, was released on 26 September 2005. Its lead single was "Nine Million Bicycles", which was released a week before the album on 19 September. The first UK airplay for the single was on the Terry Wogan show on 1 August. The album contains four more songs written by Melua herself, four more by Batt, one Batt/Melua collaboration and three more songs described as new versions of "great songs". The band line-up was the same as on the first album. The album debuted at the number-one spot on the UK Albums Chart on the week of 3 October 2005.

On 30 September 2005, Melua came under criticism in The Guardian from writer and scientist Simon Singh for the lyrics of the track "Nine Million Bicycles". Melua's disputed lyrics were:

We are 12 billion light-years from the edge. That's a guess — no-one can ever say it's true, but I know that I will always be with you.

They were interpreted by Singh as an assault on the accuracy of the work of cosmologists which sparked a series of letters from other Guardian readers, agreeing or disagreeing. On 15 October, Melua and Singh appeared on the BBC's Today programme, and Melua unveiled a re-recording of the songwhich included Singh's tongue-in-cheek amendments to the lyrics:

We are 13.7 billion light-years from the edge of the observable universe, That's a good estimate with well-defined error bars, And with the available information, I predict that I will always be with you.

Both sides amicably agreed that the new lyrics were less likely to achieve commercial success, amidst a discussion about scientific accuracy versus artistic licence. Melua said that she "should have known better" because she used to be a member of the astronomy club at school.

A double A-side of the Melua-penned "I Cried for You" and a cover of The Cure's "Just like Heaven" (1988), which is the theme song to the film Just like Heaven, was released in the UK on 5 December and peaked at number 35. "I Cried for You" was inspired by a meeting with the writer of Holy Blood, Holy Grail.

A third single, "Spider's Web" was released on 17 April 2006 and peaked at number 52 in the UK. Melua embarked on a concert tour in support of Piece by Piece, the UK leg of which started in Aberdeen, Scotland on 20 January 2006.

Towards the end of 2006, Melua released the single, "It's Only Pain", which was written by Mike Batt. This was followed by the release of "Shy Boy", also written by Batt.