"21 Summer" is a song by recorded American country music duo Brothers Osborne.

The song was released in February 2016 as the duo's fourth single overall and the third from the album Pawn Shop.

Duo members John and T.J. Osborne co-wrote the song with Craig Wiseman.

When recording the full version of the song with producer Jay Joyce, the hook was played on John's guitar and echoed by the brothers' sister, Natalie, along with bassist Pete Sternberg and Lucie Silvas, who is John Osborne's wife.

[1] After coming out as gay in February 2021, T.J. Osborne revealed that "21 Summer" was written about his first heartbreak when his relationship ended with a man he was dating in secret and he was unable to talk about it with anyone.