While recording music for their sophomore album, the group was keen in including a ballad number. Cabello told Entertainment Weekly that fans would see "more of a vulnerable side" to them. This was something that was not very present in their debut album, Reflection, she recalls, and was something all her groupmates "fought for". Ally Brooke also shared similar sentiments with Fuse when discussing the album's differences from their previous. When the group revealed the tracklist on May 6, on Instagram, Cabello stated that this was her personal favorite song, saying that the track was "an extended metaphor where you're asking somebody to "write" on you, envelop you with their words, make their mark on you like you're a blank canvas."
The song was released on streaming service Spotify and digital music platform iTunes on May 5, 2016. The track was also made available on Google Play the following day. An accompanying music video was released on the group's official Vevo channel on May 6, 2016.
Composition and lyrics
"Write on Me" was written and co-produced by Norwegian duo Mikkel Eriksen and Tor Erik Hermansen of Stargate and Kyrre Gørvell-Dahll with additional writing from Priscilla Renea and Simon Wilcox. The song is characterized by a "slow melody" in comparison to Fifth Harmony's previous works. Incorporating a tropical house sound, the song uses synths, tambourines, an acoustic guitar and finger-snaps in its instrumentation. As noted by Sasha Geffen from MTV, who described the song as blending "acoustic guitar chords with tropical synths", while using a calm instrumentation instead of "big beats". She also notes the tame atmosphere the song has from previous singles from the group.
Lyrically, the song is about a lover writing the flaws and impressions they see in their love interest, from the perspective of the group. The song opens with Kordei singing: "Pick up the pen, put it on the paper / Write on my skin, bring me to life / Can't start again, there ain't no eraser / All of my flaws, you got them so right" as Camila continues with: "Everything is blank until you draw me / Touching on my body like you know me". The pen is a metaphor for the lover's mind and the paper is represented as the love interest. The chorus features several double entendres where all members sing: "Love the way you tear me up / Baby, take your time / Write on me" implying sexual connotation.
Dana Getz of Entertainment Weekly called the song "another bop" from the group's list of "summer bangers". She notes the slower rhythm of the song, compared to previous tracks such as "Work from Home" and "The Life" but mentions the similar "anthemic" atmosphere all three songs display. Writing for Fuse, Jeff Benjamin praised the song for showcasing a "softer side" of Fifth Harmony. He notes the "euphoric, Kygo-esque beat drop" in the song while also complimenting the production of the song as it "pairs nicely" with the theme of the track. In an article published by Billboard, the magazine called the song "powerful", while also distinguishing the "laid back" atmosphere from their past single, "Work from Home". The article states that each girl is allowed their turn "in the spotlight, switching off verses on the power jam."
In a positive review, Brittany Spanos from Rolling Stone, like Benjamin, note the similar "tropical Kygo-esque house beat" and further mentions the "tender delivery" the song has "above the beat." Writing for Spin, Brennan Carley called the song "breezy and blushing", while praising the "lyrically muscular bit of summery, Kygo-esque pop-house" the song exudes. Brittany Goldfield Rodrigues from Andpop raved about the song's "infectious beat" and it's "heartfelt lyrics". She further states that the track "will give you chills, from the vocals to the lyrics". Writing for MTV, Sasha Geffen described the song as blending "acoustic guitar chords with tropical synths", while using "finger-snaps and tambourines" instead of "big beats". She also notes the tame atmosphere the song has from previous singles from the group. Lewis Corner from Digital Spy called the track "one of their most understatedly infectious bops yet, as it hears their vocals soar over a breezy, tropical-tinged production." He compliments the group for not having "suffered the dreaded second album syndrome", or sophomore slump, where the second album fails to live up to the standards of the first album.
The music video was directed by Sam Lecca and premiered on Vevo on 6 May 2016. The video, filmed in black and white, shows the five members of the group singing and dancing to the song. Regarding the video, the member Normani Kordei expressed, "this is a different approach than we've done before." She elaborates this by stating that the video focuses more on the "lyrical content" as well as their "beauty shots" which is a new concept the group explores as "there's always so much going on."