"I'm Not the Only One" is a song recorded by English singer Sam Smith from their debut studio album, In the Lonely Hour (2014).

A piano soul ballad, anchored by orchestral strings and a gospel structure, "I'm Not the Only One" deals with themes of infidelity in a relationship and was inspired by a marriage of someone Smith and Napes knew.

"[3] On 10 September 2014, a remix version of the song featuring American rapper A$AP Rocky was released worldwide through online music stores.

[7][8] In June 2024 Smith performed the song live with American singer Alicia Keys in New York City's restaurant Julius.

[18] As Smith explained in a track-by-track commentary for Digital Spy, "Napes played the chords one day and I was obsessed with them.

[20] Smith revealed to Lewis Corner that the song was the only one on the album that is not about their life, but a marriage they observed first-hand, where they put themselves into the woman's shoes.

Harley Brown of Billboard praised the track, calling it "[t]he first turning point of the record [...] where Smith goes home, dries off, and picks himself back up."

An obvious candidate for future single, it’s the type of track that elicits head bobbing and finger snapping the second it begins.

"[22] Jon Dolan of Rolling Stone called it "gorgeously bruising",[23] while Andy Kellman of AllMusic picked it as one of the album's best tracks.

[24] Eric Davidson of CMJ thought that "[t]he Al Green vibe of 'I'm Not The Only One' has a verging-on-stern sentiment couched in a deeper groove that seems like a good direction Smith could head in.

"[26] Adam Workman of The National noted that the song "really stands out among hackneyed lyrical content on love and longing; his high-pitched vocal extremes and fairly basic grasp of rhyming couplets both soon begin to rankle, too.

"[27] Ben Kelly of Attitude opined that the song is "the album's bluesy moment" [...] "echo[ing] of Sittin' on the Dock of the Bay, with Sam's strong falsetto running free as ever.

"[29] Paul Cantor of Vibe praised the song's "lush and expansive" arrangements, called it a "notably highlight" and noting that it is "brought to life by Smith's clever vocal arpeggiations and phrasings.

"[30] Rachel Sonis of Idolator defined it as "a jazzy, soothing, coffee shop-ready number that sticks to the album's 'quiet moments in life' theme", noting similarities to Adele's melancholic approach and praising the song for "show[ing] off his precious pipes more than ever before.

[53] The music video features Glee's Dianna Agron as a scorned bride and The Mindy Project's Chris Messina as the cause of and cure for her heartache.

"[55][56] Smith also claimed they wanted to "bring the song to life a bit more'" and "strike a nerve with a certain group of people".

[58] She walks him out, and then he goes straight to a bar and does shots with his mistress, while Agron's character drinks alcohol and pieces together her husband's indiscretions.

[56] While Smith performs in the saloon, Agron proceeds to uncork a bottle of white wine in the middle of her neighbourhood liquor store, drink away her problems, and then eventually set fire to Messina's possessions.