"The Missing Piece" is a song by Swedish singer and songwriter Paul Rey.

[1] Rey called the song as a journey and described that the track started "intimately and steadily grew".

[2] In an interview with escXtra, Rey revealed that "The Missing Piece" was dedicated to his daughter.

[3] Reviewing the first semi-final of Melodifestivalen 2021, William Lee Adams of Wiwibloggs praised the simplicity of the performance and called it "powerful, tender and sweet".

[4] In comparison to Rey's Melodifestivalen 2020 entry "Talking in My Sleep", Tim Jumawan of escXtra felt his growth and a more intimate feel than the former, while Dominik Rössing called "The Missing Piece" was "stronger".