Songfacts®:

• This bare break-up piano ballad finds Mars singing about a pre-fame heartbreak as he regrets a girl that he let get away. He penned the song with Miike Snow's Andrew Wyatt. "When we started the record, I was like, 'I'm never singing another ballad again,' but that came from the gut - it's the most honest, real thing I've ever sang," Mars told Rolling Stone. "When there are no safe bets, that's when I feel my blood move."
• Mars shared how important the lyrics to this song are for him when he posted a photograph of Unorthodox Jukebox's artwork via his Twitter account. "Soon you guys will hear a song I wrote called When I Was Your Man. I've never been this nervous. Can't explain it," he tweeted.
• Mars told MTV News that this ballad was inspired by some real-life heartbreak. "No, I can't fake it," he said. "I've tried and those songs have been thrown away. This song is about a special woman that I let slip away at one time. It's a happy ending though ... I put everything I got into that one.
  
  "You know it's one of those things where even girls can relate to this song. That's how it works. Everyone makes mistakes," he added. "And I remember writing that and it's the simple things, the little things. Like, I should have bought you flowers; I should have just let you know when I had the chance. And that was probably the most difficult song to write just because you know I'm so naked on that song, out of all the sexual songs I'm singing about, that's the one I'm most vulnerable. And I think a piano and a vocal is the most purest form of music."
• The music video was directed by Mars with Cameron Duddy, who also worked with Mars on the clips for "The Lazy Song" and "Locked Out of Heaven." It's filmed to look like a performance for some 1970s TV program with Mars portraying a lonely balladeer sitting in front of a piano, a half-empty glass of whiskey placed on top.
• This was only the second piano-and-vocal-only tune to top the Hot 100, following Adele's 2011 hit "Someone Like You."
• This was Bruno Mars' fifth US #1 single. He was the fastest solo male vocalist to collect five chart-toppers since Elvis Presley, needing just three years, two months and one week between the debut of his collaboration with B.O.B,"Nothin' On You," and this song's arrival at the summit. Elvis took two years, seven months and three weeks to log up his first five #1s.
  
  Bruno has another connection with The King. He started his show business career at the age of 4 as an Elvis impersonator.
• "When I Was Your Man" enjoyed a resurgence in 2023 after Miley Cyrus released her song "Flowers." Both are breakup songs from different perspectives, and the chorus of "Flowers" interpolates some the lyrics from Mars' hit single.