After being formed and finishing third in the seventh series of The X Factor in 2010, they first formed as solo singers but soon got placed as a band on 23 July 2010 One Direction were signed to Syco Music, a subsidiary of Sony Music Entertainment. "What Makes You Beautiful" was written by Savan Kotecha and Carl Falk, and was produced by Yacoub and Falk. Instrumentation was completed by Falk and Yacoub. Serban Ghenea handled the audio mixing, Tom Coyne the audio mastering, and John Hanes the mix engineering, for which Phil Seaford served as the assistant.
The song received generally positive reviews from music critics. Robert Copsey of Digital Spy gave "What Makes You Beautiful" four out of five stars, praising its catchy melody and summarising it as "adorable, completely innocent and bound to cause a stir amongst your mates". Zachary Houle of PopMatters called the song a "nice get-up-and-go dance number." Ailbhe Malone of NME commended the song's appeal to the teenage audience and its chord progression for being "simple enough to be played on an acoustic guitar at a house party." Newsround called it "fun, upbeat and incredibly catchy." AllMusic's Matthew Chisling called it an "effervescent and fresh tween love song", and chose it as one of the best tracks on Up All Night. Sophie Goddard from Cosmopolitan called the single "ridiculously catchy". Student's Jack Murray rated "What Makes You Beautiful" five out of five stars and called it "not only the best pop single of the year so far, but potentially of any X Factor contestant ever". Murray lauded the songwriting and light production. Tanner Stransky of Entertainment Weekly awarded "What Makes You Beautiful" a B+ grade, calling the song "shallow but crushworthy" and writing that the song shows that boy bands are not dying out. 
"What Makes You Beautiful" performed considerably well worldwide, but especially so in the British Isles, debuting at number 1 on the Irish Singles Chart on 15 September 2011; its B-side, "Na Na Na" also entered at number 27. The single topped the chart for four consecutive weeks. "What Makes You Beautiful" became the fourteenth best-selling single of 2011 on the Irish Singles Chart. In the UK, "What Makes You Beautiful" received the highest ever number of pre-orders for a Sony Music Entertainment single. It sold 82,000 copies in its first two days, a figure which rose to 100,000 by the third day. It entered the UK Singles Chart at number 1 on 18 September 2011, shifting 153,965 copies that week—the highest first-week UK sales for any song in 2011 at the time. "What Makes You Beautiful" also debuted at number 1 on the Scottish Singles Chart. "What Makes You Beautiful" was the 20th best-selling single of 2011, moving 540,000 copies. The single was the 92nd best-selling single of the 21st century in the UK by May 2012. As of August 2015, "What Makes You Beautiful" had sold 978,000 copies in the UK.
Digital download and CD single
- "What Makes You Beautiful" – 3:24
- "Na Na Na" – 3:10