The song was commercially successful worldwide, and reached the top ten on the singles charts of the Netherlands, Norway, Switzerland and the United Kingdom.

Since its release, "Too Lost in You" has become a staple of the group's live performances, and was included in the set lists for their tours in support of Taller in More Ways (2005), Overloaded: The Singles Collection (2006) and Change (2007).

"Too Lost in You" is a cover of "Quand j'ai peur de tout" ("When I'm Afraid of Everything"), a 1997 song performed by French singer Patricia Kaas.

[3] Warren composes her songs in an uncleaned room, where she is seated on an old stool and surrounded by keyboards, drum machines, and a tape recorder.

[4] Group member Heidi Range commented on the experience of collaborating with Warren, saying: "It could be easy to turn around and make people feel not as important as you.

[20][21] According to Harry Rubenstein of The Jerusalem Post, "[in 'Too Lost in You'] we're led to believe that these girls are actually losing control in a moment of passion, but the song refrains from moving into typical pop fairy-land characters".

[24] According to Alan Braidwood of BBC Music, the ballads from Three, including "Too Lost in You", match the quality of the group's songs "New Year" and "Stronger".

Music interpreted the song as a reminder that the Sugababes "handle trip-hop melancholy with the same devastating confidence as their seething club stomps".

[27] Writing for Hot Press, Phil Udell praised the Sugababes' performance of the ballad, which he considered a transition from Warren's "big radio number" into "something genuinely lovely".

[28] Becky Howard and Andrew Williams of the London Evening Standard wrote that "Too Lost in You" "[sweeps] you up all misty-eyed" and regarded it as "utterly brilliant" in comparison to "Caught in a Moment", another ballad from Three.

[31] Fiona Shepherd of The Scotsman dismissed lines such as "Flowing into your arms, falling into your eyes" as "lyrical gubbins" and stated that the song's release would be "for the name behind [it] rather than any individual merits".

[35][36] The song achieved more success in the group's native United Kingdom; it entered the UK Singles Chart on 25 December 2003 at number ten, a position it held for two consecutive weeks.

[63] The song was one of six tracks that they played on 20 June 2004 at Live & Loud, a music event held at Hampden Park in Glasgow, Scotland.

[65] The song was played as part of a gig in August 2004 at Delamere Forest, Cheshire, in which a critic from the Manchester Evening News wrote that the Sugababes "showed they can handle a ballad as well as the uptempo material in their vast pop catalogue".

[73] The group performed the single on 14 September 2007 at London's music club indig02, and according to Nick Levine of Digital Spy, their harmonies managed "the unfathomable trick of sounding both delicate and sturdy".

[76] In June 2009, they performed the single at the Cannock Chase Forrest as part of a 75-minute show,[77] and at Canterbury, Kent as the sixth song on the set list.

[82] Mutya Keisha Siobhan, the group's original line-up, performed the song along with "Promises", "Overload", "Run for Cover", "Freak Like Me", "Push the Button", "Hole in the Head" and "Stronger" as part of the Sacred Three tour.