The release of this album marked the beginning of A New Day..., Dion's five-year concert arrangement in The Colosseum at Caesars Palace in Las Vegas.

One Heart contains songs produced by Max Martin, Rami Yacoub, Peer Åström, Anders Bagge, Ric Wake, Kristian Lundin, Kara DioGuardi, John Shanks, Guy Roche, and others.

Another song, "Reveal", was written by Cathy Dennis, who also wrote "Toxic" for Britney Spears and "Can't Get You Out of My Head" for Kylie Minogue, among others.

Although "Have You Ever Been in Love" was already featured on Dion's previous album A New Day Has Come, it was released as the second single from One Heart in the United States and third in selected countries.

AllMusic's senior editor Stephen Thomas Erlewine rated it two-and-a-half stars out of possible five, writing that the collaboration with Britney Spears's producer Max Martin in three tracks was a sign of "desperation that underscores every minute of One Heart, where it seems like Dion will do anything to stay on the charts".

[1] Erlewine also wrote that "One Heart favors a smooth Vegas-showstopper gloss to radio-ready sheen, which only accentuates the lack of cohesiveness here" and that the album "reveals all her weaknesses".

[1] Chuck Arnold of People wrote a mixed review towards the album's songs, calling it "a bit jarring at times" and that "Dion sounds so strangely subdued on some tracks, you keep waiting for her to really let rip".

[7] Either way, he wrote positively that "There is a lightness to One Heart that has been missing from much of Dion's previous work, as she leans more toward upbeat dance numbers, easy-listening rock and even borderline country-pop".

[5] Darryl Sterdan wrote a very negative review for Jam!, saying that "it's bad enough the 14-song CD is full of unoriginal, instantly forgettable fluff -- leftover Britney bubble-pop from Max Martin, cliche chest-pounding power ballads, a title cut that's a blatant Shania soundalike and a Cher-style Eurodisco revamp of the Roy Orbison hit "I Drove All Night," which she's already turned into a Chrysler jingle".

and later went to praise the album for "Dion's uncanny ability to infuse sincerity into aural Hallmark cards and sound like the only person on earth who believes in true love".

[8] Billboard praised the album by concluding: "One Heart may not crackle with the noise of an "event" record, but it succeeds at something far more important: It is a fine piece of music".

[10] It spent eight weeks inside top ten of the Canadian Albums Chart and was certified three-times Platinum by the CRIA for shipment of 300,000 units.

It became a top ten album in many other European countries, including the United Kingdom, where it peaked at number four, was certified Gold, and has sold over 204,000 copies.