The song borrows its melody from the Cutting Crew hit single "(I Just) Died in Your Arms," which topped the American charts and peaked at #4 in the UK in 1986. Nick Van Eede of the Cutting Crew said in his Songfacts interview, "I never noticed anything until 150 fans started writing and pointing out the similarities. I know as well as any other song writer that these things can happen and its just the way of the composing world. I am completely confident Mika stumbled in to it accidentally and I am proud to be given the co write... Kerching!!!"
This originally had a limited 7" vinyl release in the UK in 2006, when it failed to chart. In the summer of 2007 it was released as a single in Europe and it topped the charts in various countries including France, Belgium and the Netherlands. The song was released as a CD single in the UK on the 31st December 2007 as a double A-side with "Lollipop."
Mika described the story behind the song in an interview with the Sun Newspaper February 2, 2007: "I always wanted to write a dance song that wasn't a really full dance track, that felt organic. So when I came into producing 'Relax' I made sure that most of the sounds we used were actually made by real instruments. We used some great session musicians who had worked with Quincy Jones and Michael Jackson. And we picked up the strangest pedal combinations to get all these weird sounds. It's really effective - you can't tell if it's a full dance track or really laid-back. It feels a bit weird electronically. The organic-ness gives a more classic field to it. So it was one of the harder tracks for me to produce, but also the most rewarding."