The lyrics consist of Lewis informing her past lover that enough time has passed since their relationship for her to have moved on and to have developed as a person.
Critics praised Lewis' vocal performance, likening her technical abilities to those of Mariah Carey and Whitney Houston.
To promote "Lovebird", Lewis performed the song on talk shows Daybreak and Loose Women in the United Kingdom, in addition to singing competition La Voz in Spain.
[9][19] The song's musical structure bears strong resemblances to one of Lewis' previous singles, "Bleeding Love", from her début studio album Spirit (2007).
[19] As power ballad beats and "airy synths" play, she sings "Your lovebird's flying away/ Cos my heart's been stuck in a cage".
[20] He further commented that it had strong radio potential, and that it would be successful if it were to be released in the United States, as it sounds like a "clone" of "Bleeding Love".
[19] Although he noted that Lewis' vocal performance on "Lovebird" is very impressive, as with all her material, he was unsure of why it was included on the final cut of the album due to Glassheart having "bigger" songs on it, which were likely to chart better.
[19] The Mirror's Clemmie Moodie thought that although the recording is a "catchy" song, it does not compare to "Bleeding Love", but noted that it does contain "lyrical gems", including "Your lovebird's flyin’ away, ’cos my heart's been stuck in a cage".
[22] Hermoine Hoby, writing on behalf of The Observer, wrote that Lewis appears to be following in the footsteps of singer-songwriter Adele, due to the inclusion of "big heartfelt ballads" such as "Lovebird" and "Fireflies" on Glassheart.
[29] Upon the release of Glassheart, "Lovebird" debuted on the South Korea Digital International Singles chart at number 73 in the issue dated 24 November 2012.
[33] In the United Kingdom, "Lovebird" was given an impact date of 9 December 2012, meaning it was only available to purchase as an album track rather than a traditional separate single release.