"Mr. Blue Sky" is a song by the Electric Light Orchestra (ELO), featured on the band's seventh studio album Out of the Blue (1977). Written and produced by frontman Jeff Lynne, the song forms the fourth and final track of the "Concerto for a Rainy Day" suite, on side three of the original double album. "Mr. Blue Sky" was the second single to be taken from Out of the Blue, peaking at number 6 in the UK Singles Chart[2] and number 35 in the US Billboard Charts.[3] Due to its popularity and frequent use in multiple television shows and movies, it has sometimes been described as the band's signature song.