It became a popular hit in 1965 when recorded by American pop and country singer Billy Joe Royal.

There have also been several other hit cover versions of this song, including by Donny Osmond and Linda Ronstadt.

"I Knew You When" was first recorded by Billy Joe Royal for his 1965 studio album, Down in the Boondocks.

[3] Linda Ronstadt recorded a cover version for her Gold-plus 1982 album, Get Closer.

Aided by a popular music video, it reached #30 on the Cash Box Top 100 chart and #37 on the Billboard Hot 100 as the album's second single.