Written and produced by the duo's members, Elly Jackson and Ben Langmaid, the song was released digitally in the United Kingdom on 21 June 2009 and physically the following day as the album's third single.

[1] It was a sleeper hit in the United States, where it peaked at number eight on the Billboard Hot 100 in June 2010, following televised performances of the song on The Ellen DeGeneres Show and Last Call with Carson Daly.

[7] Digital Spy music editor Nick Levine gave the song five stars and described it as "a bright, bouncy slice of Yazoo-ish electropop with a chorus every bit as immediate as 'In For The Kill'", adding that "Jackson's vocals are less shrill this time around, but she comes off just as formidable, informing a useless sod who's messed her about that she won't be letting him do it again.

[9] Adam R. Holz of Plugged In (publication) opined "Homage isn't a strong enough word to capture just how uncannily La Roux has repackaged that vibe of yore popularized by the likes of Erasure, The Human League, Depeche Mode and Eurythmics.

"[10] In a more mixed review from Common Sense Media, however, Stephanie Bruzzese gave "Bulletproof" two stars, calling the song a "less creative imitation of the classic tunes created by [1980s groups including Depeche Mode, Erasure, and The Human League]" and criticizing the chorus for being "nothing unique" and Jackson's vocal performance which she described as "a higher, whinier version of Alison Moyet's".

On a lighter note, she highlighted the lyrical content for being clean and the strong positive message, suggesting to parents that the song was appropriate for kids twelve years of age or older.

[11] In a September 2014 interview, Jackson expressed regrets of the song's critical and commercial success, because it was one of the reasons she was experiencing panic attacks while touring for the debut album: "I wasn't that keen on it.

As the song starts, Jackson leaves the chair and the camera pans to show random designs of La Roux which are shown behind her.