"When I Was Your Man" is a soul piano ballad about a pre-fame heartbreak as he regrets a girl that he let get away, expressing his earnest hope that her new man is giving her all the love and attention he was unwilling, or unable to provide when they were together. It received positive reviews from music critics, who praised Mars's vocals and named it a "vulnerable and emotional ballad". It charted in some countries, such as Australia, Canada, France, South Korea and the United States, where it also topped the charts.

Lyrics
 Same bed, but it feels just a little bit bigger now
 Our song on the radio, but it don't sound the same
 When our friends talk about you all that it does is just tear me down
 Cause my heart breaks a little when I hear your name
 And it all just sound like uh, uh, uh

 Hmmm too young, too dumb to realize
 That I should have bought you flowers and held your hand
 Should have gave you all my hours when I had the chance
 Take you to every party cause all you wanted to do was dance
 Now my baby is dancing, but she's dancing with another man.

 My pride, my ego, my needs and my selfish ways
 Caused a good strong woman like you to walk out my life
 Now I never, never get to clean up the mess I made
 And it haunts me every time I close my eyes
 It all just sounds like uh, uh, uh, uh

 Too young, too dumb to realize
 That I should have bought you flowers and held your hand
 Should have gave all my hours when I had the chance
 Take you to every party cause all you wanted to do was dance
 Now my baby is dancing, but she's dancing with another man.

 Although it hurts I'll be the first to say that I was wrong
 Oh, I know I'm probably much too late
 To try and apologize for my mistakes
 But I just want you to know
 I hope he buys you flowers, I hope he holds your hand
 Give you all his hours when he has the chance
 Take you to every party cause I remember how much you loved to dance
 Do all the things I should have done when I was your man!
 Do all the things I should have done when I was your man!